$BKH
BLACK HILLS CORP /SD/ Stock $bkh

$bkh Overview Financials Valuation SEC Filings Company Website

2011 Q4 Form 10-K Financial Statement

#000113046412000024 Filed on February 29, 2012

Income Statement

Concept	2011 Q4	2010 Q4	2010 Q3
Revenue	$361.2M	$315.0M	$264.4M
YoY Change	14.66%	-9.61%	17.08%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$38.20M	$37.90M	$30.04M
YoY Change	0.79%	33.45%	0.71%
% of Gross Profit
Operating Expenses	$309.0M	$252.4M	$201.6M
YoY Change	22.42%	-15.25%	-3.51%
Operating Profit	$52.14M	$46.86M	$44.70M
YoY Change	11.27%		164.33%
Interest Expense	-$23.20M	$4.600M	$24.28M
YoY Change	-604.35%	-231.43%	17.34%
% of Operating Profit	-44.5%	9.82%	54.32%
Other Income/Expense, Net	$200.0K	$700.0K	$36.88M
YoY Change	-71.43%	-69.57%	51.64%
Pretax Income	$29.10M	$40.30M	$11.07M
YoY Change	-27.79%	-18.42%	-249.36%
Income Tax	$10.30M	$12.30M	-$1.461M
% Of Pretax Income	35.4%	30.52%	-13.2%
Net Earnings	$25.59M	$33.52M	$12.39M
YoY Change	-23.65%	2.2%	-668.35%
Net Earnings / Revenue	7.09%	10.64%	4.69%
Basic Earnings Per Share	$0.61	$0.86	$0.32
Diluted Earnings Per Share	$0.60	$0.85	$0.32
COMMON SHARES
Basic Shares Outstanding	39.47M shares	39.25M shares	38.93M shares
Diluted Shares Outstanding			39.13M shares

Balance Sheet

Concept	2011 Q4	2010 Q4	2010 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$21.60M	$16.40M	$59.00M
YoY Change	31.71%	-85.47%	-57.15%
Cash & Equivalents	$21.63M	$16.44M	$58.98M
Short-Term Investments
Other Short-Term Assets	$21.27M	$14.70M	$20.93M
YoY Change	44.72%	-46.11%	-33.69%
Inventory	$84.06M	$62.92M	$145.3M
Prepaid Expenses
Receivables	$156.8M	$171.8M	$234.5M
Other Receivables	$9.300M	$0.00	$25.10M
Total Short-Term Assets	$758.9M	$684.2M	$644.6M
YoY Change	10.93%	9.49%	14.96%
LONG-TERM ASSETS
Property, Plant & Equipment	$2.790B	$2.492B	$2.363B
YoY Change	11.95%	15.32%	12.74%
Goodwill	$353.4M	$353.4M	$353.7M
YoY Change	0.0%	0.31%	0.0%
Intangibles	$3.843M	$4.069M	$4.129M
YoY Change	-5.55%	-5.57%	-12.61%
Long-Term Investments	$17.30M	$17.80M	$18.00M
YoY Change	-2.81%	-3.78%	-7.69%
Other Assets	$19.94M	$19.34M	$20.22M
YoY Change	3.11%	19.55%	157.17%
Total Long-Term Assets	$561.3M	$517.8M	$515.0M
YoY Change	8.4%	0.83%	4.58%
TOTAL ASSETS
Total Short-Term Assets	$758.9M	$684.2M	$644.6M
Total Long-Term Assets	$561.3M	$517.8M	$515.0M
Total Assets	$4.127B	$3.712B	$3.540B
YoY Change	11.2%	11.87%	11.74%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$104.7M	$146.6M	$201.1M
YoY Change	-28.53%	-36.1%	9.15%
Accrued Expenses	$151.3M	$147.6M	$167.0M
YoY Change	2.49%	-2.55%	11.29%
Deferred Revenue
YoY Change
Short-Term Debt	$345.0M	$249.0M	$145.0M
YoY Change	38.55%	51.37%	-58.63%
Long-Term Debt Due	$2.473M	$5.181M	$5.314M
YoY Change	-52.27%	-85.3%	-83.44%
Total Short-Term Liabilities	$878.1M	$793.6M	$639.0M
YoY Change	10.64%	23.07%	-23.13%
LONG-TERM LIABILITIES
Long-Term Debt	$1.280B	$1.186B	$1.188B
YoY Change	7.96%	16.75%	65.22%
Other Long-Term Liabilities	$123.6M	$128.5M	$125.7M
YoY Change	-3.86%	11.83%	1.77%
Total Long-Term Liabilities	$759.3M	$631.6M	$632.5M
YoY Change	20.22%	10.4%	13.91%
TOTAL LIABILITIES
Total Short-Term Liabilities	$878.1M	$793.6M	$639.0M
Total Long-Term Liabilities	$759.3M	$631.6M	$632.5M
Total Liabilities	$1.637B	$1.425B	$1.272B
YoY Change	14.89%	17.11%	-8.3%
SHAREHOLDERS EQUITY
Retained Earnings	$476.6M	$486.1M	$466.7M
YoY Change	-1.95%	2.58%	2.59%
Common Stock	$43.96M	$39.28M	$39.24M
YoY Change	11.91%	0.77%	0.95%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$970.0K	$309.0K	$226.0K
YoY Change	213.92%	37.95%	14.72%
Treasury Stock Shares	32.77K shares	10.96K shares	7.905K shares
Shareholders Equity	$1.209B	$1.100B	$1.080B
YoY Change
Total Liabilities & Shareholders Equity	$4.127B	$3.712B	$3.540B
YoY Change	11.2%	11.87%	11.74%

Cashflow Statement

Concept	2011 Q4	2010 Q4	2010 Q3
OPERATING ACTIVITIES
Net Income	$25.59M	$33.52M	$12.39M
YoY Change	-23.65%	2.2%	-668.35%
Depreciation, Depletion And Amortization	$38.20M	$37.90M	$30.04M
YoY Change	0.79%	33.45%	0.71%
Cash From Operating Activities	$17.20M	$22.00M	-$18.20M
YoY Change	-21.82%	-5600.0%	-173.68%
INVESTING ACTIVITIES
Capital Expenditures	-$114.2M	-$148.4M	-$152.8M
YoY Change	-23.05%	46.06%	87.48%
Acquisitions
YoY Change
Other Investing Activities	-$6.000M	$13.00M	$62.00M
YoY Change	-146.15%	-176.92%	811.76%
Cash From Investing Activities	-$120.1M	-$135.4M	-$90.80M
YoY Change	-11.3%	14.36%	21.55%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	86.90M	86.90M	103.9M
YoY Change	0.0%	-7.65%	59.11%
NET CHANGE
Cash From Operating Activities	17.20M	22.00M	-18.20M
Cash From Investing Activities	-120.1M	-135.4M	-90.80M
Cash From Financing Activities	86.90M	86.90M	103.9M
Net Change In Cash	-16.00M	-26.50M	-5.100M
YoY Change	-39.62%	7.29%	-133.33%
FREE CASH FLOW
Cash From Operating Activities	$17.20M	$22.00M	-$18.20M
Capital Expenditures	-$114.2M	-$148.4M	-$152.8M
Free Cash Flow	$131.4M	$170.4M	$134.6M
YoY Change	-22.89%	68.38%	26.74%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2011Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	104748000	USD
CY2010Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	146556000	USD
CY2010Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	171816000	USD
CY2011Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	156774000	USD
CY2011	us-gaap	Accretion Of Discount AccretionOfDiscount	19655000	USD
CY2010	us-gaap	Accretion Of Discount AccretionOfDiscount	13434000	USD
CY2009	us-gaap	Accretion Of Discount AccretionOfDiscount	19596000	USD
CY2010Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	3348000	USD
CY2011Q4	us-gaap	Accrued Income Taxes Current AccruedIncomeTaxesCurrent	0	USD
CY2010Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	147643000	USD
CY2011Q4	us-gaap	Accrued Liabilities Current AccruedLiabilitiesCurrent	151319000	USD
CY2010Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	861775000	USD
CY2011Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	934441000	USD
CY2010Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-23581000	USD
CY2011Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-32878000	USD
CY2009Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-19164000	USD
CY2011	us-gaap	Acquisition Costs AcquisitionCosts	24899000	USD
CY2010Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	598805000	USD
CY2011Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	722623000	USD
CY2009	us-gaap	Adjustments To Additional Paid In Capital Tax Effect From Share Based Compensation AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	120000	USD
CY2011	us-gaap	Adjustments To Additional Paid In Capital Tax Effect From Share Based Compensation AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	28000	USD
CY2010	us-gaap	Adjustments To Additional Paid In Capital Tax Effect From Share Based Compensation AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation	33000	USD
CY2010Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2294000	USD
CY2011Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	1661000	USD
CY2009	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	510000	shares
CY2010	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	160000	shares
CY2011	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	141000	shares
CY2010Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	42517000	USD
CY2009Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	39663000	USD
CY2011Q4	us-gaap	Asset Retirement Obligation AssetRetirementObligation	42914000	USD
CY2010	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	2675000	USD
CY2011	us-gaap	Asset Retirement Obligation Accretion Expense AssetRetirementObligationAccretionExpense	2506000	USD
CY2010	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	18664000	USD
CY2011	us-gaap	Asset Retirement Obligation Liabilities Incurred AssetRetirementObligationLiabilitiesIncurred	43000	USD
CY2010	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	17285000	USD
CY2011	us-gaap	Asset Retirement Obligation Liabilities Settled AssetRetirementObligationLiabilitiesSettled	627000	USD
CY2010	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	-1200000	USD
CY2011	us-gaap	Asset Retirement Obligation Revision Of Estimate AssetRetirementObligationRevisionOfEstimate	-1525000	USD
CY2010Q4	us-gaap	Assets Assets	3711509000	USD
CY2011Q4	us-gaap	Assets Assets	4127083000	USD
CY2010Q4	us-gaap	Assets Current AssetsCurrent	684161000	USD
CY2011Q4	us-gaap	Assets Current AssetsCurrent	758921000	USD
CY2011Q4	us-gaap	Assets Noncurrent AssetsNoncurrent	561326000	USD
CY2010Q4	us-gaap	Assets Noncurrent AssetsNoncurrent	517834000	USD
CY2011Q4	us-gaap	Assets Of Disposal Group Including Discontinued Operation AssetsOfDisposalGroupIncludingDiscontinuedOperation	340851000	USD
CY2010Q4	us-gaap	Assets Of Disposal Group Including Discontinued Operation AssetsOfDisposalGroupIncludingDiscontinuedOperation	314235000	USD
CY2011	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	37529000	USD
CY2010	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	48879000	USD
CY2009	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	24571000	USD
CY2010Q4	us-gaap	Capitalized Costs Accumulated Depreciation Depletion Amortization And Valuation Allowance For Relating To Oil And Gas Producing Activities CapitalizedCostsAccumulatedDepreciationDepletionAmortizationAndValuationAllowanceForRelatingToOilAndGasProducingActivities	334955000	USD
CY2011Q4	us-gaap	Capitalized Costs Accumulated Depreciation Depletion Amortization And Valuation Allowance For Relating To Oil And Gas Producing Activities CapitalizedCostsAccumulatedDepreciationDepletionAmortizationAndValuationAllowanceForRelatingToOilAndGasProducingActivities	361173000	USD
CY2009Q4	us-gaap	Capitalized Costs Accumulated Depreciation Depletion Amortization And Valuation Allowance For Relating To Oil And Gas Producing Activities CapitalizedCostsAccumulatedDepreciationDepletionAmortizationAndValuationAllowanceForRelatingToOilAndGasProducingActivities	335605000	USD
CY2011	us-gaap	Capitalized Costs Of Unproved Properties Excluded From Amortization CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortization	45400000	USD
CY2009Q4	us-gaap	Capitalized Costs Oil And Gas Producing Activities Gross CapitalizedCostsOilAndGasProducingActivitiesGross	611627000	USD
CY2010Q4	us-gaap	Capitalized Costs Oil And Gas Producing Activities Gross CapitalizedCostsOilAndGasProducingActivitiesGross	621138000	USD
CY2011Q4	us-gaap	Capitalized Costs Oil And Gas Producing Activities Gross CapitalizedCostsOilAndGasProducingActivitiesGross	703150000	USD
CY2011Q4	us-gaap	Capitalized Costs Oil And Gas Producing Activities Net CapitalizedCostsOilAndGasProducingActivitiesNet	341977000	USD
CY2009Q4	us-gaap	Capitalized Costs Oil And Gas Producing Activities Net CapitalizedCostsOilAndGasProducingActivitiesNet	276022000	USD
CY2010Q4	us-gaap	Capitalized Costs Oil And Gas Producing Activities Net CapitalizedCostsOilAndGasProducingActivitiesNet	286183000	USD
CY2010Q4	us-gaap	Capitalized Costs Proved Properties CapitalizedCostsProvedProperties	592978000	USD
CY2009Q4	us-gaap	Capitalized Costs Proved Properties CapitalizedCostsProvedProperties	582276000	USD
CY2011Q4	us-gaap	Capitalized Costs Proved Properties CapitalizedCostsProvedProperties	674494000	USD
CY2010Q4	us-gaap	Capitalized Costs Unproved Properties CapitalizedCostsUnprovedProperties	28160000	USD
CY2011Q4	us-gaap	Capitalized Costs Unproved Properties CapitalizedCostsUnprovedProperties	28656000	USD
CY2009Q4	us-gaap	Capitalized Costs Unproved Properties CapitalizedCostsUnprovedProperties	29351000	USD
CY2010Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	16437000	USD
CY2011Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	21628000	USD
CY2010Q4	us-gaap	Cash And Cash Equivalents At Carrying Value Including Discontinued Operations CashAndCashEquivalentsAtCarryingValueIncludingDiscontinuedOperations	32438000	USD
CY2008Q4	us-gaap	Cash And Cash Equivalents At Carrying Value Including Discontinued Operations CashAndCashEquivalentsAtCarryingValueIncludingDiscontinuedOperations	168532000	USD
CY2009Q4	us-gaap	Cash And Cash Equivalents At Carrying Value Including Discontinued Operations CashAndCashEquivalentsAtCarryingValueIncludingDiscontinuedOperations	112901000	USD
CY2011Q4	us-gaap	Cash And Cash Equivalents At Carrying Value Including Discontinued Operations CashAndCashEquivalentsAtCarryingValueIncludingDiscontinuedOperations	58768000	USD
CY2011	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	26330000	USD
CY2009	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-55631000	USD
CY2010	us-gaap	Cash And Cash Equivalents Period Increase Decrease CashAndCashEquivalentsPeriodIncreaseDecrease	-80463000	USD
CY2011	us-gaap	Cash Provided By Used In Financing Activities Discontinued Operations CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations	-158000	USD
CY2010	us-gaap	Cash Provided By Used In Financing Activities Discontinued Operations CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations	-2037000	USD
CY2009	us-gaap	Cash Provided By Used In Financing Activities Discontinued Operations CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations	-2047000	USD
CY2009	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	-220000	USD
CY2010	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	-390000	USD
CY2011	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	-2359000	USD
CY2010	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	-8813000	USD
CY2009	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	-33410000	USD
CY2011	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	7010000	USD
CY2010	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.44
CY2009	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.42
CY2011	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	1.46
CY2010Q4	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.36
CY2010Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.36
CY2010Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.36
CY2010Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.36
CY2011Q1	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.365
CY2011Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.365
CY2011Q2	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.365
CY2011Q4	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.365
CY2010Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2009Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2011Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2010Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000000	shares
CY2011Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000000	shares
CY2009Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	100000000000	shares
CY2011Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	100000000000	shares
CY2009Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	100000000000	shares
CY2010Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	100000000000	shares
CY2011Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	43957502000	shares
CY2010Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	39280048000	shares
CY2009Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	38977526000	shares
CY2011Q4	us-gaap	Common Stock Value CommonStockValue	43958000	USD
CY2010Q4	us-gaap	Common Stock Value CommonStockValue	39280000	USD
CY2010	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-4417000	USD
CY2011	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-9297000	USD
CY2009	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-381000	USD
CY2009	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-381000	USD
CY2011	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-9297000	USD
CY2010	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-4417000	USD
CY2009	us-gaap	Costs And Expenses CostsAndExpenses	341049000	USD
CY2011	us-gaap	Costs And Expenses CostsAndExpenses	375369000	USD
CY2010	us-gaap	Costs And Expenses CostsAndExpenses	351619000	USD
CY2009	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-12351000	USD
CY2010	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	678000	USD
CY2011	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	-14539000	USD
CY2009	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-12759000	USD
CY2011	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-15376000	USD
CY2010	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	4815000	USD
CY2010	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	4137000	USD
CY2009	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	-408000	USD
CY2011	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	-837000	USD
CY2011	us-gaap	Decrease Due To Sales Of Minerals In Place DecreaseDueToSalesOfMineralsInPlace	-1013000	USD
CY2009	us-gaap	Decrease Due To Sales Of Minerals In Place DecreaseDueToSalesOfMineralsInPlace	0	USD
CY2010	us-gaap	Decrease Due To Sales Of Minerals In Place DecreaseDueToSalesOfMineralsInPlace	-738000	USD
CY2010	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	20186000	USD
CY2011	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	30876000	USD
CY2009	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	45912000	USD
CY2010	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	17354000	USD
CY2009	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	45610000	USD
CY2011	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	33600000	USD
CY2011	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-246000	USD
CY2009	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-368000	USD
CY2010	us-gaap	Deferred Other Tax Expense Benefit DeferredOtherTaxExpenseBenefit	-337000	USD
CY2010	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-2495000	USD
CY2011	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	2970000	USD
CY2009	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	66000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Deferred Income DeferredTaxAssetsDeferredIncome	273000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Deferred Income DeferredTaxAssetsDeferredIncome	225000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	33824000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	19304000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Gross Current DeferredTaxAssetsGrossCurrent	34270000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Gross Current DeferredTaxAssetsGrossCurrent	52666000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	-263786000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	-255178000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Liabilities Net Current DeferredTaxAssetsLiabilitiesNetCurrent	20664000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Liabilities Net Current DeferredTaxAssetsLiabilitiesNetCurrent	37202000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Liabilities Net Noncurrent DeferredTaxAssetsLiabilitiesNetNoncurrent	-300988000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Liabilities Net Noncurrent DeferredTaxAssetsLiabilitiesNetNoncurrent	-275842000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Net Current DeferredTaxAssetsNetCurrent	37202000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Net Current DeferredTaxAssetsNetCurrent	20664000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Net Noncurrent DeferredTaxAssetsNetNoncurrent	196866000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Net Noncurrent DeferredTaxAssetsNetNoncurrent	360654000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	11538000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards State And Local DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal	9507000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	4493000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	5607000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Other Comprehensive Loss DeferredTaxAssetsOtherComprehensiveLoss	3076000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Other Comprehensive Loss DeferredTaxAssetsOtherComprehensiveLoss	2858000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	23910000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Regulatory Assets And Liabilities DeferredTaxAssetsRegulatoryAssetsAndLiabilities	40642000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Foreign DeferredTaxAssetsTaxCreditCarryforwardsForeign	2801000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Foreign DeferredTaxAssetsTaxCreditCarryforwardsForeign	3352000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	8175000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	3899000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Other DeferredTaxAssetsTaxDeferredExpenseOther	97000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Other DeferredTaxAssetsTaxDeferredExpenseOther	342000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Impairment Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses	47033000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Impairment Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsImpairmentLosses	48092000	USD
CY2010Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Loss Reserves DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves	1448000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Loss Reserves DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsLossReserves	2605000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Current DeferredTaxLiabilitiesCurrent	13606000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Current DeferredTaxLiabilitiesCurrent	15464000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Deferred Expense DeferredTaxLiabilitiesDeferredExpense	4621000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Deferred Expense DeferredTaxLiabilitiesDeferredExpense	6508000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Research And Development Costs DeferredTaxLiabilitiesDeferredExpenseCapitalizedResearchAndDevelopmentCosts	99709000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Research And Development Costs DeferredTaxLiabilitiesDeferredExpenseCapitalizedResearchAndDevelopmentCosts	94334000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	362000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Derivatives DeferredTaxLiabilitiesDerivatives	327000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	661642000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	472708000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	3161000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	3117000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	2754000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Other Comprehensive Income DeferredTaxLiabilitiesOtherComprehensiveIncome	3035000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	508261000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	314513000	USD
CY2010Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	16050000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Regulatory Assets DeferredTaxLiabilitiesRegulatoryAssets	23498000	USD
CY2011	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.0875
CY2010	us-gaap	Defined Benefit Plan Assumptions Used Calculating Net Periodic Benefit Cost Expected Long Term Return On Assets DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets	0.0925
CY2011	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Decrease On Accumulated Postretirement Benefit Obligation DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation	-2272000	USD
CY2011	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Decrease On Service And Interest Cost Components DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents	-150000	USD
CY2011	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Increase On Accumulated Postretirement Benefit Obligation DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation	2720000	USD
CY2011	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Increase On Service And Interest Cost Components DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents	184000	USD
CY2011	us-gaap	Defined Benefit Plan Health Care Cost Trend Rate Assumed For Next Fiscal Year DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYear	0.0901
CY2010	us-gaap	Defined Benefit Plan Health Care Cost Trend Rate Assumed For Next Fiscal Year DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYear	0.0951
CY2011	us-gaap	Defined Benefit Plan Measurement Date DefinedBenefitPlanMeasurementDate	December 31
CY2010	us-gaap	Defined Benefit Plan Target Allocation Percentage Of Assets Equity Securities DefinedBenefitPlanTargetAllocationPercentageOfAssetsEquitySecurities	0.65
CY2011	us-gaap	Defined Benefit Plan Target Allocation Percentage Of Assets Equity Securities DefinedBenefitPlanTargetAllocationPercentageOfAssetsEquitySecurities	0.64
CY2011	us-gaap	Defined Benefit Plan Target Allocation Percentage Of Assets Other DefinedBenefitPlanTargetAllocationPercentageOfAssetsOther	0.01
CY2010	us-gaap	Defined Benefit Plan Target Allocation Percentage Of Assets Other DefinedBenefitPlanTargetAllocationPercentageOfAssetsOther	0.01
CY2010	us-gaap	Defined Benefit Plan Target Allocation Percentage Of Assets Real Estate DefinedBenefitPlanTargetAllocationPercentageOfAssetsRealEstate	0.03
CY2011	us-gaap	Defined Benefit Plan Target Allocation Percentage Of Assets Real Estate DefinedBenefitPlanTargetAllocationPercentageOfAssetsRealEstate	0.03
CY2010	us-gaap	Defined Benefit Plan Ultimate Health Care Cost Trend Rate DefinedBenefitPlanUltimateHealthCareCostTrendRate	0.045
CY2011	us-gaap	Defined Benefit Plan Ultimate Health Care Cost Trend Rate DefinedBenefitPlanUltimateHealthCareCostTrendRate	0.045
CY2011Q4	us-gaap	Defined Benefit Plan Year That Rate Reaches Ultimate Trend Rate DefinedBenefitPlanYearThatRateReachesUltimateTrendRate	2028
CY2010Q4	us-gaap	Defined Benefit Plan Year That Rate Reaches Ultimate Trend Rate DefinedBenefitPlanYearThatRateReachesUltimateTrendRate	2027
CY2011	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	135591000	USD
CY2010	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	126606000	USD
CY2009	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	120938000	USD
CY2011Q4	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	18583000	USD
CY2010Q4	us-gaap	Derivative Assets Current DerivativeAssetsCurrent	12710000	USD
CY2011Q4	us-gaap	Derivative Assets Noncurrent DerivativeAssetsNoncurrent	1971000	USD
CY2010Q4	us-gaap	Derivative Assets Noncurrent DerivativeAssetsNoncurrent	2625000	USD
CY2009	us-gaap	Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet	55653000	USD
CY2011	us-gaap	Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet	-42010000	USD
CY2010	us-gaap	Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet	-15193000	USD
CY2010Q4	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	64617000	USD
CY2011Q4	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	84367000	USD
CY2010Q4	us-gaap	Derivative Liabilities Noncurrent DerivativeLiabilitiesNoncurrent	17897000	USD
CY2011Q4	us-gaap	Derivative Liabilities Noncurrent DerivativeLiabilitiesNoncurrent	49033000	USD
CY2011	us-gaap	Development Costs DevelopmentCosts	90100000	USD
CY2010	us-gaap	Dilutive Securities DilutiveSecurities	-288000	USD
CY2011	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves10 Percent Annual Discount For Estimated Timing Of Cash Flows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReserves10PercentAnnualDiscountForEstimatedTimingOfCashFlows	-197215000	USD
CY2010	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves10 Percent Annual Discount For Estimated Timing Of Cash Flows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReserves10PercentAnnualDiscountForEstimatedTimingOfCashFlows	-154551000	USD
CY2009	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves10 Percent Annual Discount For Estimated Timing Of Cash Flows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReserves10PercentAnnualDiscountForEstimatedTimingOfCashFlows	-96728000	USD
CY2009	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Cash Inflows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureCashInflows	-519867000	USD
CY2011	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Cash Inflows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureCashInflows	-931637000	USD
CY2010	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Cash Inflows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureCashInflows	-764585000	USD
CY2009	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Development Costs DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureDevelopmentCosts	-34961000	USD
CY2010	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Development Costs DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureDevelopmentCosts	-73805000	USD
CY2011	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Development Costs DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureDevelopmentCosts	-92233000	USD
CY2011	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Income Tax Expense DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureIncomeTaxExpense	-157922000	USD
CY2009	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Income Tax Expense DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureIncomeTaxExpense	-51287000	USD
CY2010	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Income Tax Expense DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureIncomeTaxExpense	-111666000	USD
CY2009	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Net Cash Flows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureNetCashFlows	-225836000	USD
CY2010	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Net Cash Flows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureNetCashFlows	-322659000	USD
CY2011	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Net Cash Flows DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureNetCashFlows	-400572000	USD
CY2009	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Production Costs DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureProductionCosts	-207783000	USD
CY2010	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Production Costs DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureProductionCosts	-256455000	USD
CY2011	us-gaap	Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves Future Production Costs DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesFutureProductionCosts	-280910000	USD
CY2011	us-gaap	Disposal Date DisposalDate	first quarter of 2012
CY2009Q4	us-gaap	Disposal Group Including Discontinued Operation Cash And Cash Equivalents DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	97500000	USD
CY2010Q4	us-gaap	Disposal Group Including Discontinued Operation Cash And Cash Equivalents DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	16000000	USD
CY2008Q4	us-gaap	Disposal Group Including Discontinued Operation Cash And Cash Equivalents DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	94700000	USD
CY2011Q4	us-gaap	Disposal Group Including Discontinued Operation Cash And Cash Equivalents DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	37100000	USD
CY2009	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	55151000	USD
CY2011	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	59202000	USD
CY2010	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	56467000	USD
CY2010	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.76
CY2009	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.11
CY2011	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.25
CY2010Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.86
CY2010Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.22
CY2010Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.32
CY2010Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.81
CY2011Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.2
CY2011Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.61
CY2011Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.27
CY2011Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.69
CY2009	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.11
CY2011	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.24
CY2010	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.76
CY2010Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.32
CY2010Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.22
CY2010Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.85
CY2010Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.81
CY2011Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.68
CY2011Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.27
CY2011Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.6
CY2011Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.19
CY2010	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	-0.26
CY2009	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	-0.295
CY2011	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	-0.311
CY2011	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2009	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2010	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35
CY2011	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.005
CY2009	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.003
CY2010	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.004
CY2010	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.011
CY2009	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	-0.003
CY2011	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.018
CY2010	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0.012
CY2011	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	0.028
CY2009	us-gaap	Effective Income Tax Rate Reconciliation Tax Contingencies EffectiveIncomeTaxRateReconciliationTaxContingencies	-0.021
CY2011	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.000
CY2009	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0.000
CY2010	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	-0.032
CY2011Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	7100000	USD
CY2011	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition	1.8	years
CY2011	us-gaap	Equity Issuance Dates EquityIssuanceDates	2010-11-10
CY2011	us-gaap	Exploration Costs ExplorationCosts	16745000	USD
CY2011	us-gaap	Extensions Discoveries Additions And Improved Recovery Less Related Costs ExtensionsDiscoveriesAdditionsAndImprovedRecoveryLessRelatedCosts	31179000	USD
CY2009	us-gaap	Extensions Discoveries Additions And Improved Recovery Less Related Costs ExtensionsDiscoveriesAdditionsAndImprovedRecoveryLessRelatedCosts	3324000	USD
CY2010	us-gaap	Extensions Discoveries Additions And Improved Recovery Less Related Costs ExtensionsDiscoveriesAdditionsAndImprovedRecoveryLessRelatedCosts	17076000	USD
CY2011	us-gaap	Gross Profit GrossProfit	697199000	USD
CY2011Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	7043000	USD
CY2010Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	6126000	USD
CY2009Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	5844000	USD
CY2011	us-gaap	Finite Lived Intangible Assets Amortization Expense FiniteLivedIntangibleAssetsAmortizationExpense	226000	USD
CY2009	us-gaap	Finite Lived Intangible Assets Amortization Expense FiniteLivedIntangibleAssetsAmortizationExpense	210000	USD
CY2010	us-gaap	Finite Lived Intangible Assets Amortization Expense FiniteLivedIntangibleAssetsAmortizationExpense	240000	USD
CY2011	us-gaap	Finite Lived Intangible Assets Useful Life Maximum FiniteLivedIntangibleAssetsUsefulLifeMaximum	20	years
CY2011	us-gaap	Future Amortization Expense Year Five FutureAmortizationExpenseYearFive	200000	USD
CY2011	us-gaap	Future Amortization Expense Year Four FutureAmortizationExpenseYearFour	200000	USD
CY2011	us-gaap	Future Amortization Expense Year One FutureAmortizationExpenseYearOne	200000	USD
CY2011	us-gaap	Future Amortization Expense Year Three FutureAmortizationExpenseYearThree	200000	USD
CY2011	us-gaap	Future Amortization Expense Year Two FutureAmortizationExpenseYearTwo	200000	USD
CY2009	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	25971000	USD
CY2011	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	0	USD
CY2010	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	8921000	USD
CY2010Q1	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	2700000	USD
CY2010Q3	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	6200000	USD
CY2009	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	25971000	USD
CY2010	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	8921000	USD
CY2011	us-gaap	Gain Loss On Sale Of Property Plant Equipment GainLossOnSaleOfPropertyPlantEquipment	0	USD
CY2011Q4	us-gaap	Goodwill Goodwill	353396000	USD
CY2010Q4	us-gaap	Goodwill Goodwill	353396000	USD
CY2009Q4	us-gaap	Goodwill Goodwill	352299000	USD
CY2011	us-gaap	Goodwill Allocation Adjustment GoodwillAllocationAdjustment	0	USD
CY2009	us-gaap	Goodwill Allocation Adjustment GoodwillAllocationAdjustment	7880000	USD
CY2010	us-gaap	Goodwill Allocation Adjustment GoodwillAllocationAdjustment	0	USD
CY2011	us-gaap	Goodwill Other Changes GoodwillOtherChanges	0	USD
CY2010	us-gaap	Goodwill Other Changes GoodwillOtherChanges	1097000	USD
CY2010	us-gaap	Gross Profit GrossProfit	652724000	USD
CY2011Q4	us-gaap	Guarantee Obligations Maximum Exposure GuaranteeObligationsMaximumExposure	139805000	USD
CY2009	us-gaap	Gross Profit GrossProfit	603472000	USD
CY2011	us-gaap	Impairment Of Oil And Gas Properties ImpairmentOfOilAndGasProperties	0	USD
CY2009	us-gaap	Impairment Of Oil And Gas Properties ImpairmentOfOilAndGasProperties	43301000	USD
CY2010	us-gaap	Impairment Of Oil And Gas Properties ImpairmentOfOilAndGasProperties	0	USD
CY2009	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	77269000	USD
CY2011	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	40365000	USD
CY2010	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	63141000	USD
CY2010Q3	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	10493000	USD
CY2010Q2	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	-10688000	USD
CY2010Q1	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	28705000	USD
CY2010Q4	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	34631000	USD
CY2011Q1	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	29068000	USD
CY2011Q4	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	18754000	USD
CY2011Q3	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	-11163000	USD
CY2011Q2	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	3706000	USD
CY2011	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	57468000	USD
CY2010	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	83751000	USD
CY2009	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	108777000	USD
CY2010	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.62
CY2009	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	2
CY2011	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	1.01
CY2010Q4	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.89
CY2010Q2	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.27
CY2010Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.27
CY2010Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.74
CY2011Q2	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.09
CY2011Q3	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	-0.29
CY2011Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.74
CY2011Q4	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	0.45
CY2009	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	2
CY2010	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.62
CY2011	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	1.01
CY2010Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.27
CY2010Q2	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.27
CY2010Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.74
CY2010Q4	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.88
CY2011Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.73
CY2011Q4	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.44
CY2011Q3	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	-0.29
CY2011Q2	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	0.09
CY2011	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	9365000	USD
CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	5544000	USD
CY2009	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	4286000	USD
CY2010Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-1111000	USD
CY2010Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	1897000	USD
CY2010Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	2029000	USD
CY2010Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	2729000	USD
CY2011Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	6839000	USD
CY2011Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-2158000	USD
CY2011Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	4046000	USD
CY2011Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	638000	USD
CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.14
CY2009	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.11
CY2011	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.24
CY2010Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.05
CY2010Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.07
CY2010Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.05
CY2010Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	-0.03
CY2011Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.02
CY2011Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.16
CY2011Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	-0.05
CY2011Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0.11
CY2010	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.14
CY2011	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.23
CY2009	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.11
CY2010Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.03
CY2010Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.05
CY2010Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.07
CY2010Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.05
CY2011Q3	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.02
CY2011Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	-0.05
CY2011Q2	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.1
CY2011Q4	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0.16
CY2009	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	1343000	USD
CY2010	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	1559000	USD
CY2011	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	1121000	USD
CY2009Q4	us-gaap	Income Tax Examination Liability Refund Adjustment From Settlement With Taxing Authority IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority	-59136000	USD
CY2010Q4	us-gaap	Income Tax Examination Liability Refund Adjustment From Settlement With Taxing Authority IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority	0	USD
CY2011Q4	us-gaap	Income Tax Examination Liability Refund Adjustment From Settlement With Taxing Authority IncomeTaxExaminationLiabilityRefundAdjustmentFromSettlementWithTaxingAuthority	0	USD
CY2011	us-gaap	Income Tax Examination Year S Under Examination IncomeTaxExaminationYearSUnderExamination	2007 through 2009
CY2010	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	22169000	USD
CY2009	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	32851000	USD
CY2011	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	18224000	USD
CY2011	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-9854000	USD
CY2010	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-9384000	USD
CY2009	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-17117000	USD
CY2011Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	9344000	USD
CY2010Q4	us-gaap	Income Taxes Receivable IncomeTaxesReceivable	0	USD
CY2010	us-gaap	Increase Decrease In Estimated Future Development Costs IncreaseDecreaseInEstimatedFutureDevelopmentCosts	-17125000	USD
CY2009	us-gaap	Increase Decrease In Estimated Future Development Costs IncreaseDecreaseInEstimatedFutureDevelopmentCosts	83000000	USD
CY2011	us-gaap	Increase Decrease In Estimated Future Development Costs IncreaseDecreaseInEstimatedFutureDevelopmentCosts	43809000	USD
CY2009	us-gaap	Increase Decrease In Fair Value Of Unhedged Derivative Instruments IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstruments	55653000	USD
CY2010	us-gaap	Increase Decrease In Fair Value Of Unhedged Derivative Instruments IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstruments	-15193000	USD
CY2011	us-gaap	Increase Decrease In Fair Value Of Unhedged Derivative Instruments IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstruments	-42010000	USD
CY2010	us-gaap	Increase Decrease In Future Income Tax Expense Estimates On Future Cash Flows Related To Proved Oil And Gas Reserves IncreaseDecreaseInFutureIncomeTaxExpenseEstimatesOnFutureCashFlowsRelatedToProvedOilAndGasReserves	-23233000	USD
CY2009	us-gaap	Increase Decrease In Future Income Tax Expense Estimates On Future Cash Flows Related To Proved Oil And Gas Reserves IncreaseDecreaseInFutureIncomeTaxExpenseEstimatesOnFutureCashFlowsRelatedToProvedOilAndGasReserves	11520000	USD
CY2011	us-gaap	Increase Decrease In Future Income Tax Expense Estimates On Future Cash Flows Related To Proved Oil And Gas Reserves IncreaseDecreaseInFutureIncomeTaxExpenseEstimatesOnFutureCashFlowsRelatedToProvedOilAndGasReserves	-23283000	USD
CY2011	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	21385000	USD
CY2009	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	-36767000	USD
CY2010	us-gaap	Increase Decrease In Inventories IncreaseDecreaseInInventories	338000	USD
CY2011	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-31091000	USD
CY2010	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	-12848000	USD
CY2009	us-gaap	Increase Decrease In Other Accounts Payable And Accrued Liabilities IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities	4404000	USD
CY2011	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	11118000	USD
CY2009	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-7091000	USD
CY2010	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	1013000	USD
CY2009	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	-2598000	USD
CY2010	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	21283000	USD
CY2011	us-gaap	Increase Decrease In Other Regulatory Assets IncreaseDecreaseInOtherRegulatoryAssets	-12691000	USD
CY2011	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	11198000	USD
CY2010	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	50000	USD
CY2009	us-gaap	Increase Decrease In Regulatory Liabilities IncreaseDecreaseInRegulatoryLiabilities	1265000	USD
CY2010	us-gaap	Increase Due To Purchases Of Minerals In Place IncreaseDueToPurchasesOfMineralsInPlace	0	USD
CY2009	us-gaap	Increase Due To Purchases Of Minerals In Place IncreaseDueToPurchasesOfMineralsInPlace	0	USD
CY2011	us-gaap	Increase Due To Purchases Of Minerals In Place IncreaseDueToPurchasesOfMineralsInPlace	0	USD
CY2010Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	4069000	USD
CY2011Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	3843000	USD
CY2009Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	4309000	USD
CY2008Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	4884000	USD
CY2011	us-gaap	Interest Costs Incurred InterestCostsIncurred	116684000	USD
CY2009	us-gaap	Interest Costs Incurred InterestCostsIncurred	89441000	USD
CY2010	us-gaap	Interest Costs Incurred InterestCostsIncurred	105676000	USD
CY2009	us-gaap	Interest Expense InterestExpense	83253000	USD
CY2011	us-gaap	Interest Expense InterestExpense	91383000	USD
CY2010	us-gaap	Interest Expense InterestExpense	90606000	USD
CY2010	us-gaap	Interest Paid Net InterestPaidNet	101947000	USD
CY2009	us-gaap	Interest Paid Net InterestPaidNet	69317000	USD
CY2011	us-gaap	Interest Paid Net InterestPaidNet	103110000	USD
CY2011Q4	us-gaap	Interest Rate Cash Flow Hedge Gain Loss To Be Reclassified During Next12 Months Net InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet	6500000	USD
CY2011Q4	us-gaap	Inventory Net InventoryNet	84064000	USD
CY2010Q4	us-gaap	Inventory Net InventoryNet	62915000	USD
CY2011Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	40838000	USD
CY2010Q4	us-gaap	Inventory Raw Materials And Supplies InventoryRawMaterialsAndSupplies	31537000	USD
CY2009	us-gaap	Investment Income Interest InvestmentIncomeInterest	923000	USD
CY2011	us-gaap	Investment Income Interest InvestmentIncomeInterest	2017000	USD
CY2010	us-gaap	Investment Income Interest InvestmentIncomeInterest	541000	USD
CY2011Q4	us-gaap	Investment Owned Subject To Option Price InvestmentOwnedSubjectToOptionPrice	2.55	USD
CY2011Q4	us-gaap	Jointly Owned Utility Plant Gross Ownership Amount Of Plant In Service JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService	363300000	USD
CY2011Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress	1847000	USD
CY2011Q4	us-gaap	Jointly Owned Utility Plant Ownership Amount Of Plant Accumulated Depreciation JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation	78539000	USD
CY2009	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	3939000	USD
CY2011	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	6125000	USD
CY2010	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	4219000	USD
CY2011Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	43700000	USD
CY2010Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	46865000	USD
CY2010Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	3711509000	USD
CY2011Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	4127083000	USD
CY2011Q4	us-gaap	Liabilities Current LiabilitiesCurrent	878067000	USD
CY2010Q4	us-gaap	Liabilities Current LiabilitiesCurrent	793611000	USD
CY2010Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	631578000	USD
CY2011Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	759271000	USD
CY2010Q4	us-gaap	Liabilities Of Disposal Group Including Discontinued Operation LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation	173323000	USD
CY2011Q4	us-gaap	Liabilities Of Disposal Group Including Discontinued Operation LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation	173929000	USD
CY2010Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	50135000	USD
CY2009Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	107088000	USD
CY2008Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	120022000	USD
CY2011Q4	us-gaap	Liability For Uncertain Tax Positions Noncurrent LiabilityForUncertainTaxPositionsNoncurrent	49327000	USD
CY2011Q4	us-gaap	Long Term Debt LongTermDebt	1282882000	USD
CY2010Q4	us-gaap	Long Term Debt LongTermDebt	1191231000	USD
CY2011Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	2473000	USD
CY2010Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	5181000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal After Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive	597054000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	2473000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Five LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive	85101000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	6964000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	262473000	USD
CY2011Q4	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	328973000	USD
CY2010Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1186050000	USD
CY2011Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	1280409000	USD
CY2011Q4	us-gaap	Long Term Investments LongTermInvestments	17261000	USD
CY2010Q4	us-gaap	Long Term Investments LongTermInvestments	17780000	USD
CY2010	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	160953000	USD
CY2011	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	249633000	USD
CY2009	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-56310000	USD
CY2009	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	-54263000	USD
CY2010	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	162990000	USD
CY2011	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	249791000	USD
CY2011	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-447007000	USD
CY2010	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-389168000	USD
CY2009	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-269823000	USD
CY2009	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-269603000	USD
CY2011	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-444648000	USD
CY2010	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-388778000	USD
CY2010	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	147752000	USD
CY2009	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	270502000	USD
CY2011	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	223704000	USD
CY2010	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	156565000	USD
CY2011	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	216694000	USD
CY2009	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	303912000	USD
CY2010	us-gaap	Net Income Loss NetIncomeLoss	68685000	USD
CY2011	us-gaap	Net Income Loss NetIncomeLoss	49730000	USD
CY2009	us-gaap	Net Income Loss NetIncomeLoss	81555000	USD
CY2010Q3	us-gaap	Net Income Loss NetIncomeLoss	12390000	USD
CY2010Q4	us-gaap	Net Income Loss NetIncomeLoss	33520000	USD
CY2010Q1	us-gaap	Net Income Loss NetIncomeLoss	31434000	USD
CY2010Q2	us-gaap	Net Income Loss NetIncomeLoss	-8659000	USD
CY2011Q4	us-gaap	Net Income Loss NetIncomeLoss	25593000	USD
CY2011Q3	us-gaap	Net Income Loss NetIncomeLoss	-10525000	USD
CY2011Q1	us-gaap	Net Income Loss NetIncomeLoss	26910000	USD
CY2011Q2	us-gaap	Net Income Loss NetIncomeLoss	7752000	USD
CY2010	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	68685000	USD
CY2011	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	49730000	USD
CY2009	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	81555000	USD
CY2010	us-gaap	Net Increase Decrease In Sales And Transfer Prices And Production Costs NetIncreaseDecreaseInSalesAndTransferPricesAndProductionCosts	57380000	USD
CY2009	us-gaap	Net Increase Decrease In Sales And Transfer Prices And Production Costs NetIncreaseDecreaseInSalesAndTransferPricesAndProductionCosts	-40786000	USD
CY2011	us-gaap	Net Increase Decrease In Sales And Transfer Prices And Production Costs NetIncreaseDecreaseInSalesAndTransferPricesAndProductionCosts	57087000	USD
CY2011	us-gaap	Operating Income Loss OperatingIncomeLoss	186239000	USD
CY2009	us-gaap	Operating Income Loss OperatingIncomeLoss	124155000	USD
CY2010	us-gaap	Operating Income Loss OperatingIncomeLoss	183420000	USD
CY2009	us-gaap	Operating Expenses OperatingExpenses	1074557000	USD
CY2010	us-gaap	Operating Expenses OperatingExpenses	1036271000	USD
CY2010Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	46857000	USD
CY2010Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	44695000	USD
CY2010Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	64698000	USD
CY2010Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	27170000	USD
CY2011	us-gaap	Operating Expenses OperatingExpenses	1085949000	USD
CY2011Q1	us-gaap	Operating Income Loss OperatingIncomeLoss	58367000	USD
CY2011Q4	us-gaap	Operating Income Loss OperatingIncomeLoss	52140000	USD
CY2011Q2	us-gaap	Operating Income Loss OperatingIncomeLoss	36160000	USD
CY2011Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	39572000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	14498000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	2799000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	1403000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	1912000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	2376000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	2398000	USD
CY2011Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	3610000	USD
CY2010Q4	us-gaap	Other Assets Current OtherAssetsCurrent	14695000	USD
CY2011Q4	us-gaap	Other Assets Current OtherAssetsCurrent	21266000	USD
CY2011Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	19941000	USD
CY2010Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	19339000	USD
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Cost Credit Arising During Period Before Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax	-501000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Cost Credit Arising During Period Before Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax	-325000	USD
CY2009	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Cost Credit Arising During Period Before Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax	9202000	USD
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	325000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	214000	USD
CY2009	us-gaap	Other Comprehensive Income Defined Benefit Plan Net Prior Service Costs Credit Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostsCreditArisingDuringPeriodNetOfTax	-5971000	USD
CY2009	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Period Increase Decrease OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPeriodIncreaseDecrease	4491000	USD
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Period Increase Decrease OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPeriodIncreaseDecrease	-7934000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Period Increase Decrease OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPeriodIncreaseDecrease	-1521000	USD
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-7609000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-1307000	USD
CY2009	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-1501000	USD
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plans Tax OtherComprehensiveIncomeDefinedBenefitPlansTax	4135000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plans Tax OtherComprehensiveIncomeDefinedBenefitPlansTax	674000	USD
CY2009	us-gaap	Other Comprehensive Income Defined Benefit Plans Tax OtherComprehensiveIncomeDefinedBenefitPlansTax	812000	USD
CY2011	us-gaap	Other Comprehensive Income Loss Before Tax Period Increase Decrease OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecrease	-14607000	USD
CY2010	us-gaap	Other Comprehensive Income Loss Before Tax Period Increase Decrease OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecrease	-7064000	USD
CY2009	us-gaap	Other Comprehensive Income Loss Before Tax Period Increase Decrease OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecrease	-710000	USD
CY2009	us-gaap	Other Comprehensive Income Loss Net Of Tax Period Increase Decrease OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease	-81174000	USD
CY2010	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	2647000	USD
CY2009	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	329000	USD
CY2011	us-gaap	Other Comprehensive Income Minimum Pension Liability Net Adjustment Before Tax OtherComprehensiveIncomeMinimumPensionLiabilityNetAdjustmentBeforeTax	-11744000	USD
CY2010	us-gaap	Other Comprehensive Income Minimum Pension Liability Net Adjustment Before Tax OtherComprehensiveIncomeMinimumPensionLiabilityNetAdjustmentBeforeTax	-1981000	USD
CY2009	us-gaap	Other Comprehensive Income Minimum Pension Liability Net Adjustment Before Tax OtherComprehensiveIncomeMinimumPensionLiabilityNetAdjustmentBeforeTax	-2313000	USD
CY2010	us-gaap	Other Comprehensive Income Loss Net Of Tax Period Increase Decrease OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease	-64268000	USD
CY2011	us-gaap	Other Comprehensive Income Loss Net Of Tax Period Increase Decrease OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease	-40433000	USD
CY2011	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	5310000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Before Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeBeforeTax	2177000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Before Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeBeforeTax	-6730000	USD
CY2009	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Before Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeBeforeTax	19810000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeNetOfTax	-1468000	USD
CY2009	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeNetOfTax	-12609000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeNetOfTax	4232000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeTax	709000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeTax	-2498000	USD
CY2009	us-gaap	Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeTax	7201000	USD
CY2009	us-gaap	Other Comprehensive Income Reclassification Of Defined Benefit Plan Net Transition Asset Obligation Recognized In Net Periodic Benefit Cost Before Tax OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlanNetTransitionAssetObligationRecognizedInNetPeriodicBenefitCostBeforeTax	33000	USD
CY2009	us-gaap	Other Comprehensive Income Reclassification Of Defined Benefit Plan Net Transition Asset Obligation Recognized In Net Periodic Benefit Cost Net Of Tax OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlanNetTransitionAssetObligationRecognizedInNetPeriodicBenefitCostNetOfTax	21000	USD
CY2009	us-gaap	Other Comprehensive Income Reclassification Of Defined Benefit Plant Net Transition Asset Obligation Recognized In Net Periodic Benefit Cost Tax OtherComprehensiveIncomeReclassificationOfDefinedBenefitPlantNetTransitionAssetObligationRecognizedInNetPeriodicBenefitCostTax	12000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-4539000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	1972000	USD
CY2009	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-27442000	USD
CY2009	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	-17481000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	1336000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	-2831000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	1708000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	-636000	USD
CY2009	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	9961000	USD
CY2009	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	1230000	USD
CY2011	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	710000	USD
CY2010	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	980000	USD
CY2011	us-gaap	Other Expenses OtherExpenses	817000	USD
CY2010	us-gaap	Other Expenses OtherExpenses	140000	USD
CY2009	us-gaap	Other Expenses OtherExpenses	513000	USD
CY2011	us-gaap	Other Income OtherIncome	2490000	USD
CY2010	us-gaap	Other Income OtherIncome	2733000	USD
CY2009	us-gaap	Other Income OtherIncome	5921000	USD
CY2010Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	128519000	USD
CY2011Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	123553000	USD
CY2011	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-10602000	USD
CY2010	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	3851000	USD
CY2009	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-4539000	USD
CY2009	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	12642000	USD
CY2011	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	3726000	USD
CY2010	us-gaap	Other Nonoperating Income Expense OtherNonoperatingIncomeExpense	7148000	USD
CY2009	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	15494000	USD
CY2010	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-15407000	USD
CY2011	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	4533000	USD
CY2009	us-gaap	Payments Of Dividends PaymentsOfDividends	55151000	USD
CY2011	us-gaap	Payments Of Dividends PaymentsOfDividends	59202000	USD
CY2010	us-gaap	Payments Of Dividends PaymentsOfDividends	56467000	USD
CY2011	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	0	USD
CY2009	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	0	USD
CY2010	us-gaap	Payments To Acquire Businesses Gross PaymentsToAcquireBusinessesGross	2250000	USD
CY2010	us-gaap	Payments To Acquire Other Property Plant And Equipment PaymentsToAcquireOtherPropertyPlantAndEquipment	472292000	USD
CY2009	us-gaap	Payments To Acquire Other Property Plant And Equipment PaymentsToAcquireOtherPropertyPlantAndEquipment	346650000	USD
CY2011	us-gaap	Payments To Acquire Other Property Plant And Equipment PaymentsToAcquireOtherPropertyPlantAndEquipment	440698000	USD
CY2010	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	16342000	USD
CY2009	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	16349000	USD
CY2011	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	14586000	USD
CY2010Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	124709000	USD
CY2011Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	177480000	USD
CY2009	us-gaap	Pension Contributions PensionContributions	16945000	USD
CY2010	us-gaap	Pension Contributions PensionContributions	30015000	USD
CY2011	us-gaap	Pension Contributions PensionContributions	11050000	USD
CY2009	us-gaap	Previously Estimated Development Costs Incurred During Period PreviouslyEstimatedDevelopmentCostsIncurredDuringPeriod	4620000	USD
CY2011	us-gaap	Previously Estimated Development Costs Incurred During Period PreviouslyEstimatedDevelopmentCostsIncurredDuringPeriod	18940000	USD
CY2010	us-gaap	Previously Estimated Development Costs Incurred During Period PreviouslyEstimatedDevelopmentCostsIncurredDuringPeriod	4975000	USD
CY2010	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	3246000	USD
CY2011	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	123041000	USD
CY2009	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	4819000	USD
CY2011	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2010	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	200000000	USD
CY2009	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	543069000	USD
CY2009	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	586000000	USD
CY2010	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	854500000	USD
CY2011	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	1017300000	USD
CY2011	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-1666000	USD
CY2009	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-5527000	USD
CY2010	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-8363000	USD
CY2010	us-gaap	Proceeds From Sale Of Other Property Plant And Equipment ProceedsFromSaleOfOtherPropertyPlantAndEquipment	70357000	USD
CY2009	us-gaap	Proceeds From Sale Of Other Property Plant And Equipment ProceedsFromSaleOfOtherPropertyPlantAndEquipment	84661000	USD
CY2011	us-gaap	Proceeds From Sale Of Other Property Plant And Equipment ProceedsFromSaleOfOtherPropertyPlantAndEquipment	583000	USD
CY2011Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	3724016000	USD
CY2010Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	3353509000	USD
CY2010	us-gaap	Property Plant And Equipment Gross Period Increase Decrease PropertyPlantAndEquipmentGrossPeriodIncreaseDecrease	496990000	USD
CY2011	us-gaap	Property Plant And Equipment Gross Period Increase Decrease PropertyPlantAndEquipmentGrossPeriodIncreaseDecrease	431707000	USD
CY2010Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	2491734000	USD
CY2011Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	2789575000	USD
CY2011	us-gaap	Property Plant And Equipment Preproduction Design And Development Costs PropertyPlantAndEquipmentPreproductionDesignAndDevelopmentCosts	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Development Costs</font></div><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">According to accounting standards for business combinations, we expense, when incurred, development and acquisition costs associated with corporate development activities prior to acquiring or beginning construction of a project. Expensed development costs are included in Other operating expenses on the accompanying Consolidated Statements of Income.</font></div></div>
CY2011	us-gaap	Proved Developed And Undeveloped Reserves Extensions Discoveries And Additions ProvedDevelopedAndUndevelopedReservesExtensionsDiscoveriesAndAdditions	35.2	Bcfe
CY2010	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	2996000	USD
CY2011	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	932000	USD
CY2009	us-gaap	Public Utilities Allowance For Funds Used During Construction Capitalized Cost Of Equity PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity	5891000	USD
CY2010Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	138405000	USD
CY2011Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	59955000	USD
CY2010Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	66429000	USD
CY2011Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	182175000	USD
CY2010Q4	us-gaap	Regulatory Assets RegulatoryAssets	204834000	USD
CY2011Q4	us-gaap	Regulatory Assets RegulatoryAssets	242130000	USD
CY2010Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	88554000	USD
CY2011Q4	us-gaap	Regulatory Liabilities RegulatoryLiabilities	124448000	USD
CY2010Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	3943000	USD
CY2011Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	16231000	USD
CY2011Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	108217000	USD
CY2010Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	84611000	USD
CY2011	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	821300000	USD
CY2009	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	1125300000	USD
CY2010	us-gaap	Repayments Of Lines Of Credit RepaymentsOfLinesOfCredit	770000000	USD
CY2010	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	59926000	USD
CY2011	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	8382000	USD
CY2009	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	2173000	USD
CY2010Q4	us-gaap	Restricted Cash And Investments Current RestrictedCashAndInvestmentsCurrent	4260000	USD
CY2011Q4	us-gaap	Restricted Cash And Investments Current RestrictedCashAndInvestmentsCurrent	9254000	USD
CY2010	us-gaap	Results Of Operations Depreciation Depletion And Amortization And Valuation Provisions ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions	29013000	USD
CY2009	us-gaap	Results Of Operations Depreciation Depletion And Amortization And Valuation Provisions ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions	72338000	USD
CY2011	us-gaap	Results Of Operations Depreciation Depletion And Amortization And Valuation Provisions ResultsOfOperationsDepreciationDepletionAndAmortizationAndValuationProvisions	34415000	USD
CY2010	us-gaap	Results Of Operations Expense From Oil And Gas Producing Activities ResultsOfOperationsExpenseFromOilAndGasProducingActivities	50935000	USD
CY2011	us-gaap	Results Of Operations Expense From Oil And Gas Producing Activities ResultsOfOperationsExpenseFromOilAndGasProducingActivities	58235000	USD
CY2009	us-gaap	Results Of Operations Expense From Oil And Gas Producing Activities ResultsOfOperationsExpenseFromOilAndGasProducingActivities	93991000	USD
CY2011	us-gaap	Results Of Operations Income Before Income Taxes ResultsOfOperationsIncomeBeforeIncomeTaxes	21573000	USD
CY2010	us-gaap	Results Of Operations Income Before Income Taxes ResultsOfOperationsIncomeBeforeIncomeTaxes	23229000	USD
CY2009	us-gaap	Results Of Operations Income Before Income Taxes ResultsOfOperationsIncomeBeforeIncomeTaxes	-23307000	USD
CY2010	us-gaap	Results Of Operations Income Tax Expense ResultsOfOperationsIncomeTaxExpense	8014000	USD
CY2011	us-gaap	Results Of Operations Income Tax Expense ResultsOfOperationsIncomeTaxExpense	7442000	USD
CY2009	us-gaap	Results Of Operations Income Tax Expense ResultsOfOperationsIncomeTaxExpense	-8041000	USD
CY2009	us-gaap	Results Of Operations Production Or Lifting Costs ResultsOfOperationsProductionOrLiftingCosts	21653000	USD
CY2010	us-gaap	Results Of Operations Production Or Lifting Costs ResultsOfOperationsProductionOrLiftingCosts	21922000	USD
CY2011	us-gaap	Results Of Operations Production Or Lifting Costs ResultsOfOperationsProductionOrLiftingCosts	23820000	USD
CY2009	us-gaap	Results Of Operations Revenue From Oil And Gas Producing Activities ResultsOfOperationsRevenueFromOilAndGasProducingActivities	70684000	USD
CY2010	us-gaap	Results Of Operations Revenue From Oil And Gas Producing Activities ResultsOfOperationsRevenueFromOilAndGasProducingActivities	74164000	USD
CY2011	us-gaap	Results Of Operations Revenue From Oil And Gas Producing Activities ResultsOfOperationsRevenueFromOilAndGasProducingActivities	79808000	USD
CY2010Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	486075000	USD
CY2011Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	476603000	USD
CY2009	us-gaap	Revenues From Transactions With Other Operating Segments Of Same Entity RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity	486000	USD
CY2011	us-gaap	Revenues From Transactions With Other Operating Segments Of Same Entity RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity	0	USD
CY2010	us-gaap	Revenues From Transactions With Other Operating Segments Of Same Entity RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity	4621000	USD
CY2009	us-gaap	Revisions Of Previous Quantity Estimates RevisionsOfPreviousQuantityEstimates	-104556000	USD
CY2010	us-gaap	Revisions Of Previous Quantity Estimates RevisionsOfPreviousQuantityEstimates	27513000	USD
CY2011	us-gaap	Revisions Of Previous Quantity Estimates RevisionsOfPreviousQuantityEstimates	-58211000	USD
CY2011	us-gaap	Sales And Transfers Of Oil And Gas Produced Net Of Production Costs SalesAndTransfersOfOilAndGasProducedNetOfProductionCosts	-52914000	USD
CY2009	us-gaap	Sales And Transfers Of Oil And Gas Produced Net Of Production Costs SalesAndTransfersOfOilAndGasProducedNetOfProductionCosts	-26836000	USD
CY2010	us-gaap	Sales And Transfers Of Oil And Gas Produced Net Of Production Costs SalesAndTransfersOfOilAndGasProducedNetOfProductionCosts	-40282000	USD
CY2009	us-gaap	Sales Revenue Net SalesRevenueNet	1198712000	USD
CY2010	us-gaap	Sales Revenue Net SalesRevenueNet	1219691000	USD
CY2011	us-gaap	Sales Revenue Net SalesRevenueNet	1272188000	USD
CY2010Q3	us-gaap	Sales Revenue Net SalesRevenueNet	240521000	USD
CY2010Q1	us-gaap	Sales Revenue Net SalesRevenueNet	416728000	USD
CY2010Q4	us-gaap	Sales Revenue Net SalesRevenueNet	314999000	USD
CY2010Q2	us-gaap	Sales Revenue Net SalesRevenueNet	247443000	USD
CY2011Q1	us-gaap	Sales Revenue Net SalesRevenueNet	400835000	USD
CY2011Q4	us-gaap	Sales Revenue Net SalesRevenueNet	361181000	USD
CY2011Q3	us-gaap	Sales Revenue Net SalesRevenueNet	249523000	USD
CY2011Q2	us-gaap	Sales Revenue Net SalesRevenueNet	260649000	USD
CY2010	us-gaap	Share Based Compensation ShareBasedCompensation	5637000	USD
CY2011	us-gaap	Share Based Compensation ShareBasedCompensation	5643000	USD
CY2009	us-gaap	Share Based Compensation ShareBasedCompensation	3908000	USD
CY2009Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Total Share Based Liabilities Paid ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTotalShareBasedLiabilitiesPaid	0	USD
CY2010Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Total Share Based Liabilities Paid ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTotalShareBasedLiabilitiesPaid	0	USD
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Term ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedTerm	7	years
CY2009	us-gaap	Segment Reporting Information Revenue SegmentReportingInformationRevenue	1198226000	USD
CY2011	us-gaap	Segment Reporting Information Revenue SegmentReportingInformationRevenue	1272188000	USD
CY2010	us-gaap	Segment Reporting Information Revenue SegmentReportingInformationRevenue	1215070000	USD
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate	0.046
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate	0.29
CY2011	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate	0.026
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	961476	shares
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber	165000	shares
CY2011Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice	29.57
CY2011Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	345000000	USD
CY2010Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	249000000	USD
CY2009	us-gaap	Standardized Measure Of Discounted Future Net Cash Flow Of Proved Oil And Gas Reserves Period Increase Decrease StandardizedMeasureOfDiscountedFutureNetCashFlowOfProvedOilAndGasReservesPeriodIncreaseDecrease	-129108000	USD
CY2010	us-gaap	Standardized Measure Of Discounted Future Net Cash Flow Of Proved Oil And Gas Reserves Period Increase Decrease StandardizedMeasureOfDiscountedFutureNetCashFlowOfProvedOilAndGasReservesPeriodIncreaseDecrease	-168108000	USD
CY2011	us-gaap	Standardized Measure Of Discounted Future Net Cash Flow Of Proved Oil And Gas Reserves Period Increase Decrease StandardizedMeasureOfDiscountedFutureNetCashFlowOfProvedOilAndGasReservesPeriodIncreaseDecrease	-203357000	USD
CY2010Q4	us-gaap	Standardized Measure Of Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves StandardizedMeasureOfDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReserves	168108000	USD
CY2011Q4	us-gaap	Standardized Measure Of Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves StandardizedMeasureOfDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReserves	203357000	USD
CY2008Q4	us-gaap	Standardized Measure Of Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves StandardizedMeasureOfDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReserves	179226000	USD
CY2009Q4	us-gaap	Standardized Measure Of Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves StandardizedMeasureOfDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReserves	129108000	USD
CY2011	us-gaap	Stock Issued During Period Shares Treasury Stock Reissued StockIssuedDuringPeriodSharesTreasuryStockReissued	0	shares
CY2010	us-gaap	Stock Issued During Period Shares Treasury Stock Reissued StockIssuedDuringPeriodSharesTreasuryStockReissued	0	shares
CY2009	us-gaap	Stock Issued During Period Shares Treasury Stock Reissued StockIssuedDuringPeriodSharesTreasuryStockReissued	0	shares
CY2011	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	3202000	USD
CY2009	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	2241000	USD
CY2010	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	3141000	USD
CY2011	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	119630000	USD
CY2011	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	5076000	USD
CY2009	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	6157000	USD
CY2010	us-gaap	Stock Issued During Period Value Share Based Compensation StockIssuedDuringPeriodValueShareBasedCompensation	4817000	USD
CY2010Q4	us-gaap	Stockholders Equity StockholdersEquity	1100270000	USD
CY2011Q4	us-gaap	Stockholders Equity StockholdersEquity	1209336000	USD
CY2009Q4	us-gaap	Stockholders Equity StockholdersEquity	1084837000	USD
CY2008Q4	us-gaap	Stockholders Equity StockholdersEquity	1050536000	USD
CY2010	us-gaap	Stockholders Equity Other StockholdersEquityOther	-5000	USD
CY2011	us-gaap	Stockholders Equity Other StockholdersEquityOther	-45000	USD
CY2010	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	27592000	USD
CY2011	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	33710000	USD
CY2009	us-gaap	Taxes Excluding Income And Excise Taxes TaxesExcludingIncomeAndExciseTaxes	21687000	USD
CY2011Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	32766000	shares
CY2010Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	10962000	shares
CY2009Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	8834000	shares
CY2011Q4	us-gaap	Treasury Stock Value TreasuryStockValue	970000	USD
CY2010Q4	us-gaap	Treasury Stock Value TreasuryStockValue	309000	USD
CY2010	us-gaap	Unrealized Gain Loss On Derivatives UnrealizedGainLossOnDerivatives	-13546000	USD
CY2011	us-gaap	Unrealized Gain Loss On Derivatives UnrealizedGainLossOnDerivatives	8693000	USD
CY2009	us-gaap	Unrealized Gain Loss On Derivatives UnrealizedGainLossOnDerivatives	-19083000	USD
CY2011	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	3533000	USD
CY2009	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	18686000	USD
CY2010	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions	76545000	USD
CY2009	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2010	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2011	us-gaap	Unrecognized Tax Benefits Decreases Resulting From Settlements With Taxing Authorities UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities	0	USD
CY2010Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	3100000	USD
CY2011Q4	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	4500000	USD
CY2009	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	1200000	USD
CY2011	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	1400000	USD
CY2010	us-gaap	Unrecognized Tax Benefits Income Tax Penalties And Interest Expense UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense	2300000	USD
CY2010	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2009	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2011	us-gaap	Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions	0	USD
CY2009	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	5752000	USD
CY2010	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	19592000	USD
CY2011	us-gaap	Unrecognized Tax Benefits Increases Resulting From Prior Period Tax Positions UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions	2725000	USD
CY2010Q4	us-gaap	Unrecognized Tax Benefits Resulting In Net Operating Loss Carryforward UnrecognizedTaxBenefitsResultingInNetOperatingLossCarryforward	63779000	USD
CY2011Q4	us-gaap	Unrecognized Tax Benefits Resulting In Net Operating Loss Carryforward UnrecognizedTaxBenefitsResultingInNetOperatingLossCarryforward	195834000	USD
CY2011Q4	us-gaap	Unrecognized Tax Benefits That Would Impact Effective Tax Rate UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate	1100000	USD
CY2011Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Fifth Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary	46568000	USD
CY2011Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On First Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary	199811000	USD
CY2011Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Fourth Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary	70140000	USD
CY2011Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Second Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary	123600000	USD
CY2011Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Balance On Third Anniversary UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary	73145000	USD
CY2011Q4	us-gaap	Unrecorded Unconditional Purchase Obligation Due After Five Years UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears	202779000	USD
CY2009	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	107074000	USD
CY2011	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	116669000	USD
CY2010	us-gaap	Unregulated Operating Revenue UnregulatedOperatingRevenue	109930000	USD
CY2011	us-gaap	Use Of Estimates UseOfEstimates	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Use of Estimates and Basis of Presentation</font></div><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of certain assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management evaluates its estimates and related assumptions regularly, including, but not limited to, those related to the market value of derivatives, intangible asset valuations and useful lives, long-lived asset values and useful lives, proved oil and gas reserve volumes, actuarially determined employee benefit costs, valuation of deferred taxes and contingencies. Changes in facts and circumstances or additional information may result in revised estimates and actual results could differ materially from those estimates.</font></div></div>
CY2010	us-gaap	Utilities Operating Expense Maintenance Operations And Other Costs And Expenses UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses	251375000	USD
CY2011	us-gaap	Utilities Operating Expense Maintenance Operations And Other Costs And Expenses UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses	247496000	USD
CY2009	us-gaap	Utilities Operating Expense Maintenance Operations And Other Costs And Expenses UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses	241995000	USD
CY2011	us-gaap	Utility Revenue UtilityRevenue	1155519000	USD
CY2009	us-gaap	Utility Revenue UtilityRevenue	1091638000	USD
CY2010	us-gaap	Utility Revenue UtilityRevenue	1109761000	USD
CY2010	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	0	USD
CY2011	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	0	USD
CY2009	us-gaap	Valuation Allowances And Reserves Adjustments ValuationAllowancesAndReservesAdjustments	0	USD
CY2010Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	2295000	USD
CY2008Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	3916000	USD
CY2011Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	1661000	USD
CY2009Q4	us-gaap	Valuation Allowances And Reserves Balance ValuationAllowancesAndReservesBalance	3683000	USD
CY2010	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	1898000	USD
CY2011	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	3042000	USD
CY2009	us-gaap	Valuation Allowances And Reserves Charged To Cost And Expense ValuationAllowancesAndReservesChargedToCostAndExpense	4078000	USD
CY2011	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	-9045000	USD
CY2009	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	-7540000	USD
CY2010	us-gaap	Valuation Allowances And Reserves Deductions ValuationAllowancesAndReservesDeductions	-5482000	USD
CY2009	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	3229000	USD
CY2011	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	5369000	USD
CY2010	us-gaap	Valuation Allowances And Reserves Recoveries ValuationAllowancesAndReservesRecoveries	2196000	USD
CY2009	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	38684000	shares
CY2011	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	40081000	shares
CY2010	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	39091000	shares
CY2010	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	38916000	shares
CY2009	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	38614000	shares
CY2011	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	39864000	shares
CY2011Q4	us-gaap	Wells In Process Of Drilling WellsInProcessOfDrilling	1219	Wells
CY2009	bkh	Accounts Receivable And Other Current Assets AccountsReceivableAndOtherCurrentAssets	26593000	USD
CY2011	bkh	Accounts Receivable And Other Current Assets AccountsReceivableAndOtherCurrentAssets	-4202000	USD
CY2010	bkh	Accounts Receivable And Other Current Assets AccountsReceivableAndOtherCurrentAssets	-18480000	USD
CY2010	bkh	Asset Retirement Cost Depreciation Expense AssetRetirementCostDepreciationExpense	6519000	USD
CY2009	bkh	Asset Retirement Cost Depreciation Expense AssetRetirementCostDepreciationExpense	1993000	USD
CY2011	bkh	Asset Retirement Cost Depreciation Expense AssetRetirementCostDepreciationExpense	5212000	USD
CY2011	bkh	Capital Expenditure For Proved Undeveloped Reserve CapitalExpenditureForProvedUndevelopedReserve	18900000	USD
CY2011	bkh	Capitalized Interest CapitalizedInterest	11260000	USD
CY2010	bkh	Capitalized Interest CapitalizedInterest	4381000	USD
CY2009	bkh	Capitalized Interest CapitalizedInterest	349000	USD
CY2011	bkh	Capitalized Interest Of Cost Excluded From Amortization CapitalizedInterestOfCostExcludedFromAmortization	3756000	USD
CY2011	bkh	Change In Deferred Liabilities Net Related To Acquisition ChangeInDeferredLiabilitiesNetRelatedToAcquisition	0	USD
CY2010	bkh	Change In Deferred Liabilities Net Related To Acquisition ChangeInDeferredLiabilitiesNetRelatedToAcquisition	-784000	USD
CY2010	bkh	Change In Deferred Liabilities Net Related To Net Operating Loss From Acquisition ChangeInDeferredLiabilitiesNetRelatedToNetOperatingLossFromAcquisition	-312000	USD
CY2011	bkh	Change In Deferred Liabilities Net Related To Net Operating Loss From Acquisition ChangeInDeferredLiabilitiesNetRelatedToNetOperatingLossFromAcquisition	0	USD
CY2011	bkh	Change In Deferred Liabilities Net Related To Other ChangeInDeferredLiabilitiesNetRelatedToOther	-215000	USD
CY2010	bkh	Change In Deferred Liabilities Net Related To Other ChangeInDeferredLiabilitiesNetRelatedToOther	731000	USD
CY2011	bkh	Change In Deferred Tax Liabilities Net ChangeInDeferredTaxLiabilitiesNet	8608000	USD
CY2010	bkh	Change In Deferred Tax Liabilities Net ChangeInDeferredTaxLiabilitiesNet	414000	USD
CY2010	bkh	Change In Deferred Tax Liabilities Net Related To Other Comprehensive Income ChangeInDeferredTaxLiabilitiesNetRelatedToOtherComprehensiveIncome	1915000	USD
CY2011	bkh	Change In Deferred Tax Liabilities Net Related To Other Comprehensive Income ChangeInDeferredTaxLiabilitiesNetRelatedToOtherComprehensiveIncome	2259000	USD
CY2011	bkh	Change In Deferred Tax Liabilities Net Related To Regulatory Assets And Liabilities ChangeInDeferredTaxLiabilitiesNetRelatedToRegulatoryAssetsAndLiabilities	22962000	USD
CY2010	bkh	Change In Deferred Tax Liabilities Net Related To Regulatory Assets And Liabilities ChangeInDeferredTaxLiabilitiesNetRelatedToRegulatoryAssetsAndLiabilities	25511000	USD
CY2011	bkh	Changes In Deferred Tax Liabilities Net Related To Property Basis Differences ChangesInDeferredTaxLiabilitiesNetRelatedToPropertyBasisDifferences	-14000	USD
CY2010	bkh	Changes In Deferred Tax Liabilities Net Related To Property Basis Differences ChangesInDeferredTaxLiabilitiesNetRelatedToPropertyBasisDifferences	-10121000	USD
CY2009Q1	bkh	Crude Oil Price Per Barrel Nymex CrudeOilPricePerBarrelNymex	49.66
CY2011Q4	bkh	Crude Oil Price Per Barrel Nymex CrudeOilPricePerBarrelNymex	96.19
CY2010Q4	bkh	Crude Oil Price Per Barrel Nymex CrudeOilPricePerBarrelNymex	79.43
CY2009Q4	bkh	Crude Oil Price Per Barrel Nymex CrudeOilPricePerBarrelNymex	61.18
CY2009Q1	bkh	Crude Oil Price Per Barrel Wellhead CrudeOilPricePerBarrelWellhead	45.32
CY2011Q4	bkh	Crude Oil Price Per Barrel Wellhead CrudeOilPricePerBarrelWellhead	88.49
CY2009Q4	bkh	Crude Oil Price Per Barrel Wellhead CrudeOilPricePerBarrelWellhead	53.59
CY2010Q4	bkh	Crude Oil Price Per Barrel Wellhead CrudeOilPricePerBarrelWellhead	70.82
CY2010Q4	bkh	Deferred Tax Asset Development Operations DeferredTaxAssetDevelopmentOperations	594000	USD
CY2011Q4	bkh	Deferred Tax Asset Development Operations DeferredTaxAssetDevelopmentOperations	614000	USD
CY2011Q4	bkh	Deferred Tax Asset Non Current Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetNonCurrentTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	14313000	USD
CY2010Q4	bkh	Deferred Tax Asset Non Current Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetNonCurrentTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	11533000	USD
CY2011Q4	bkh	Deferred Tax Asset Unbilled Revenues DeferredTaxAssetUnbilledRevenues	0	USD
CY2010Q4	bkh	Deferred Tax Asset Unbilled Revenues DeferredTaxAssetUnbilledRevenues	0	USD
CY2011Q4	bkh	Deferred Tax Assets Non Current Derivative Instruments DeferredTaxAssetsNonCurrentDerivativeInstruments	5275000	USD
CY2010Q4	bkh	Deferred Tax Assets Non Current Derivative Instruments DeferredTaxAssetsNonCurrentDerivativeInstruments	3038000	USD
CY2010Q4	bkh	Deferred Tax Assets Non Current Other DeferredTaxAssetsNonCurrentOther	11076000	USD
CY2011Q4	bkh	Deferred Tax Assets Non Current Other DeferredTaxAssetsNonCurrentOther	9453000	USD
CY2010Q4	bkh	Deferred Tax Assets Non Current Other Comprehensive Income DeferredTaxAssetsNonCurrentOtherComprehensiveIncome	22306000	USD
CY2011Q4	bkh	Deferred Tax Assets Non Current Other Comprehensive Income DeferredTaxAssetsNonCurrentOtherComprehensiveIncome	33540000	USD
CY2010Q4	bkh	Deferred Tax Assets Non Current Tax Deferred Expense Other DeferredTaxAssetsNonCurrentTaxDeferredExpenseOther	0	USD
CY2011Q4	bkh	Deferred Tax Assets Non Current Tax Deferred Expense Other DeferredTaxAssetsNonCurrentTaxDeferredExpenseOther	0	USD
CY2011Q4	bkh	Deferred Tax Liabilities Non Current Deferred Costs DeferredTaxLiabilitiesNonCurrentDeferredCosts	9155000	USD
CY2010Q4	bkh	Deferred Tax Liabilities Non Current Deferred Costs DeferredTaxLiabilitiesNonCurrentDeferredCosts	17615000	USD
CY2010Q4	bkh	Deferred Tax Liabilities Non Current Derivatives DeferredTaxLiabilitiesNonCurrentDerivatives	0	USD
CY2011Q4	bkh	Deferred Tax Liabilities Non Current Derivatives DeferredTaxLiabilitiesNonCurrentDerivatives	0	USD
CY2011Q4	bkh	Deferred Tax Liabilities Non Current Other DeferredTaxLiabilitiesNonCurrentOther	9729000	USD
CY2010Q4	bkh	Deferred Tax Liabilities Non Current Other DeferredTaxLiabilitiesNonCurrentOther	8942000	USD
CY2010Q4	bkh	Deferred Tax Liabilities Reserves And Accruals Loss Reserves DeferredTaxLiabilitiesReservesAndAccrualsLossReserves	312000	USD
CY2011Q4	bkh	Deferred Tax Liabilities Reserves And Accruals Loss Reserves DeferredTaxLiabilitiesReservesAndAccrualsLossReserves	0	USD
CY2011Q4	bkh	Deferred Tax Liability Non Current Other Comprehensive Income DeferredTaxLiabilityNonCurrentOtherComprehensiveIncome	2054000	USD
CY2010Q4	bkh	Deferred Tax Liability Non Current Other Comprehensive Income DeferredTaxLiabilityNonCurrentOtherComprehensiveIncome	4402000	USD
CY2010Q4	bkh	Deferred Tax Liability Prepaid Expenses DeferredTaxLiabilityPrepaidExpenses	2431000	USD
CY2011Q4	bkh	Deferred Tax Liability Prepaid Expenses DeferredTaxLiabilityPrepaidExpenses	2442000	USD
CY2010Q4	bkh	Deferred Tax Liability State DeferredTaxLiabilityState	11477000	USD
CY2011Q4	bkh	Deferred Tax Liability State DeferredTaxLiabilityState	14611000	USD
CY2010	bkh	Defined Benefit Plan Target Allocation Percentage Of Assets Fixed Income DefinedBenefitPlanTargetAllocationPercentageOfAssetsFixedIncome	0.31
CY2011	bkh	Defined Benefit Plan Target Allocation Percentage Of Assets Fixed Income DefinedBenefitPlanTargetAllocationPercentageOfAssetsFixedIncome	0.32
CY2011	bkh	Defined Benefit Plan Target Asset Allocations Total DefinedBenefitPlanTargetAssetAllocationsTotal	-1
CY2010	bkh	Defined Benefit Plan Target Asset Allocations Total DefinedBenefitPlanTargetAssetAllocationsTotal	-1
CY2011	bkh	Defined Contribution Plan Maximum Annual Contribution Per Employee Percent DefinedContributionPlanMaximumAnnualContributionPerEmployeePercent	0.5
CY2011	bkh	Defined Contribution Plan Requisite Service Period DefinedContributionPlanRequisiteServicePeriod	5	years
CY2011	bkh	Discount Rate Of After Tax Future Net Cash Flows DiscountRateOfAfterTaxFutureNetCashFlows	0.1
CY2011	bkh	Effective Income Tax Rate Income Tax Reconciliation Excess Percentage Depletion EffectiveIncomeTaxRateIncomeTaxReconciliationExcessPercentageDepletion	-0.025
CY2010	bkh	Effective Income Tax Rate Income Tax Reconciliation Excess Percentage Depletion EffectiveIncomeTaxRateIncomeTaxReconciliationExcessPercentageDepletion	-0.017
CY2009	bkh	Effective Income Tax Rate Income Tax Reconciliation Excess Percentage Depletion EffectiveIncomeTaxRateIncomeTaxReconciliationExcessPercentageDepletion	-0.008
CY2010	bkh	Effective Income Tax Rate Reconciliation Allowance For Other Funds Used During Construction EffectiveIncomeTaxRateReconciliationAllowanceForOtherFundsUsedDuringConstruction	-0.010
CY2011	bkh	Effective Income Tax Rate Reconciliation Allowance For Other Funds Used During Construction EffectiveIncomeTaxRateReconciliationAllowanceForOtherFundsUsedDuringConstruction	-0.005
CY2009	bkh	Effective Income Tax Rate Reconciliation Allowance For Other Funds Used During Construction EffectiveIncomeTaxRateReconciliationAllowanceForOtherFundsUsedDuringConstruction	-0.017
CY2010	bkh	Effective Income Tax Rate Reconciliation Amortization Of Investment Tax Credits EffectiveIncomeTaxRateReconciliationAmortizationOfInvestmentTaxCredits	-0.004
CY2009	bkh	Effective Income Tax Rate Reconciliation Amortization Of Investment Tax Credits EffectiveIncomeTaxRateReconciliationAmortizationOfInvestmentTaxCredits	-0.003
CY2011	bkh	Effective Income Tax Rate Reconciliation Amortization Of Investment Tax Credits EffectiveIncomeTaxRateReconciliationAmortizationOfInvestmentTaxCredits	-0.005
CY2011	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.045
CY2009	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	0.000
CY2010	bkh	Effective Income Tax Rate Reconciliation Flow Through Accounting EffectiveIncomeTaxRateReconciliationFlowThroughAccounting	-0.046
CY2011	bkh	Expected Volatility Historical Cost ExpectedVolatilityHistoricalCost	0.5
CY2011	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	0	USD
CY2009	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	365000	USD
CY2010	bkh	Finite Lived Intangible Asset Purchase Accounting Adjustments FiniteLivedIntangibleAssetPurchaseAccountingAdjustments	0	USD
CY2009	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	595240000	USD
CY2010	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	566967000	USD
CY2011	bkh	Fuel Purchased Power And Cost Of Gas Sold FuelPurchasedPowerAndCostOfGasSold	574989000	USD
CY2010Q1	bkh	Gain Loss On Disposition Of Assets Net Of Tax GainLossOnDispositionOfAssetsNetOfTax	1700000	USD
CY2010Q3	bkh	Gain Loss On Disposition Of Assets Net Of Tax GainLossOnDispositionOfAssetsNetOfTax	4100000	USD
CY2011Q4	bkh	Gas And Oil Acreage Leased GasAndOilAcreageLeased	328643	Acres
CY2010Q2	bkh	Increase Decrease In Fair Value Of Unhedged Derivative Instrument After Tax IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstrumentAfterTax	-16200000	USD
CY2011Q4	bkh	Increase Decrease In Fair Value Of Unhedged Derivative Instrument After Tax IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstrumentAfterTax	-900000	USD
CY2010Q3	bkh	Increase Decrease In Fair Value Of Unhedged Derivative Instrument After Tax IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstrumentAfterTax	-8900000	USD
CY2011Q2	bkh	Increase Decrease In Fair Value Of Unhedged Derivative Instrument After Tax IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstrumentAfterTax	-5100000	USD
CY2010Q1	bkh	Increase Decrease In Fair Value Of Unhedged Derivative Instrument After Tax IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstrumentAfterTax	-2000000	USD
CY2011Q3	bkh	Increase Decrease In Fair Value Of Unhedged Derivative Instrument After Tax IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstrumentAfterTax	-24900000	USD
CY2011Q1	bkh	Increase Decrease In Fair Value Of Unhedged Derivative Instrument After Tax IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstrumentAfterTax	3600000	USD
CY2010Q4	bkh	Increase Decrease In Fair Value Of Unhedged Derivative Instrument After Tax IncreaseDecreaseInFairValueOfUnhedgedDerivativeInstrumentAfterTax	17200000	USD
CY2009	bkh	Incremental Common Shares Attributable To Other Dilutive Securities IncrementalCommonSharesAttributableToOtherDilutiveSecurities	4000	shares
CY2010	bkh	Incremental Common Shares Attributable To Other Dilutive Securities IncrementalCommonSharesAttributableToOtherDilutiveSecurities	25000	shares
CY2011	bkh	Incremental Common Shares Attributable To Other Dilutive Securities IncrementalCommonSharesAttributableToOtherDilutiveSecurities	45000	shares
CY2009	bkh	Incremental Common Shares Attributable To Share Based Payment Arrangements Options IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsOptions	0	shares
CY2010	bkh	Incremental Common Shares Attributable To Share Based Payment Arrangements Options IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsOptions	14000	shares
CY2011	bkh	Incremental Common Shares Attributable To Share Based Payment Arrangements Options IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsOptions	19000	shares
CY2009	bkh	Incremental Common Shares Attributable To Share Based Payment Arrangements Restricted Stock And Restricted Stock Units IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsRestrictedStockAndRestrictedStockUnits	66000	shares
CY2011	bkh	Incremental Common Shares Attributable To Share Based Payment Arrangements Restricted Stock And Restricted Stock Units IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsRestrictedStockAndRestrictedStockUnits	153000	shares
CY2010	bkh	Incremental Common Shares Attributable To Share Based Payment Arrangements Restricted Stock And Restricted Stock Units IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsRestrictedStockAndRestrictedStockUnits	107000	shares
CY2010	bkh	Incremental Shares Attributable To Equity Forward Agreement IncrementalSharesAttributableToEquityForwardAgreement	29000	shares
CY2009	bkh	Incremental Shares Attributable To Equity Forward Agreement IncrementalSharesAttributableToEquityForwardAgreement	0	shares
CY2011	bkh	Incremental Shares Attributable To Equity Forward Agreement IncrementalSharesAttributableToEquityForwardAgreement	0	shares
CY2011Q4	bkh	Liabilities For Uncertain Tax Position Net LiabilitiesForUncertainTaxPositionNet	49327000	USD
CY2010Q4	bkh	Liabilities For Uncertain Tax Position Net LiabilitiesForUncertainTaxPositionNet	50135000	USD
CY2009Q4	bkh	Liabilities For Uncertain Tax Position Net LiabilitiesForUncertainTaxPositionNet	47952000	USD
CY2010Q3	bkh	Market Price Per Share Low MarketPricePerShareLow	27.79
CY2010Q4	bkh	Market Price Per Share Low MarketPricePerShareLow	29.32
CY2010Q1	bkh	Market Price Per Share Low MarketPricePerShareLow	25.65
CY2010Q2	bkh	Market Price Per Share Low MarketPricePerShareLow	27.34
CY2011Q2	bkh	Market Price Per Share Low MarketPricePerShareLow	28.12
CY2011Q4	bkh	Market Price Per Share Low MarketPricePerShareLow	29.10
CY2011Q1	bkh	Market Price Per Share Low MarketPricePerShareLow	29.76
CY2011Q3	bkh	Market Price Per Share Low MarketPricePerShareLow	25.83
CY2010Q2	bkh	Market Prices Per Share High MarketPricesPerShareHigh	34.49
CY2010Q3	bkh	Market Prices Per Share High MarketPricesPerShareHigh	33.31
CY2010Q4	bkh	Market Prices Per Share High MarketPricesPerShareHigh	33.42
CY2010Q1	bkh	Market Prices Per Share High MarketPricesPerShareHigh	30.83
CY2011Q2	bkh	Market Prices Per Share High MarketPricesPerShareHigh	34.85
CY2011Q4	bkh	Natural Gas Price Per Mcf Wellhead NaturalGasPricePerMcfWellhead	3.59
CY2010Q4	bkh	Natural Gas Price Per Mcf Wellhead NaturalGasPricePerMcfWellhead	3.45
CY2009Q4	bkh	Natural Gas Price Per Mcf Wellhead NaturalGasPricePerMcfWellhead	2.52
CY2011	bkh	Non Cash Refinancing Of Debt NonCashRefinancingOfDebt	0	USD
CY2011Q4	bkh	Market Prices Per Share High MarketPricesPerShareHigh	34.47
CY2011Q1	bkh	Market Prices Per Share High MarketPricesPerShareHigh	33.64
CY2011Q3	bkh	Market Prices Per Share High MarketPricesPerShareHigh	32.22
CY2009Q1	bkh	Natural Gas Price Per Mcf Nymex NaturalGasPricePerMcfNymex	3.63
CY2011Q4	bkh	Natural Gas Price Per Mcf Nymex NaturalGasPricePerMcfNymex	4.12
CY2009Q4	bkh	Natural Gas Price Per Mcf Nymex NaturalGasPricePerMcfNymex	3.87
CY2010Q4	bkh	Natural Gas Price Per Mcf Nymex NaturalGasPricePerMcfNymex	4.38
CY2009Q1	bkh	Natural Gas Price Per Mcf Wellhead NaturalGasPricePerMcfWellhead	2.23
CY2010	bkh	Non Cash Refinancing Of Debt NonCashRefinancingOfDebt	0	USD
CY2009	bkh	Non Cash Refinancing Of Debt NonCashRefinancingOfDebt	17000000	USD
CY2010	bkh	Non Cash Revision To Capitalized Asset Retirement Costs NonCashRevisionToCapitalizedAssetRetirementCosts	1858000	USD
CY2009	bkh	Non Cash Revision To Capitalized Asset Retirement Costs NonCashRevisionToCapitalizedAssetRetirementCosts	6027000	USD
CY2011	bkh	Non Cash Revision To Capitalized Asset Retirement Costs NonCashRevisionToCapitalizedAssetRetirementCosts	1525000	USD
CY2011	bkh	Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans Net Prior Service Cost Recognized In Net Periodic Costs Tax OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostRecognizedInNetPeriodicCostsTax	-176000	USD
CY2010	bkh	Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans Net Prior Service Cost Recognized In Net Periodic Costs Tax OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostRecognizedInNetPeriodicCostsTax	-111000	USD
CY2009	bkh	Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans Net Prior Service Cost Recognized In Net Periodic Costs Tax OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostRecognizedInNetPeriodicCostsTax	3231000	USD
CY2010	bkh	Other Comprehensive Income Reclassification Adjustment Other Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOtherNetOfTax	0	USD
CY2011	bkh	Other Comprehensive Income Reclassification Adjustment Other Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOtherNetOfTax	0	USD
CY2009	bkh	Other Comprehensive Income Reclassification Adjustment Other Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentOtherNetOfTax	0	USD
CY2010	bkh	Overhead Of Discontinued Operations OverheadOfDiscontinuedOperations	3515000000	USD
CY2011	bkh	Overhead Of Discontinued Operations OverheadOfDiscontinuedOperations	3418000000	USD
CY2009	bkh	Overhead Of Discontinued Operations OverheadOfDiscontinuedOperations	3753000000	USD
CY2011Q4	bkh	Performance Share Award Payout Cash Percentage PerformanceShareAwardPayoutCashPercentage	0.5
CY2011Q4	bkh	Performance Share Award Payout Percentage Of Target Maximum PerformanceShareAwardPayoutPercentageOfTargetMaximum	1.75
CY2011Q4	bkh	Performance Share Award Payout Percentage Of Target Minimum PerformanceShareAwardPayoutPercentageOfTargetMinimum	0
CY2011Q4	bkh	Performance Share Award Payout Shares Percentage PerformanceShareAwardPayoutSharesPercentage	0.5
CY2011Q4	bkh	Proved Developed Reserves Mcfe ProvedDevelopedReservesMcfe	32.4	Bcfe
CY2011Q4	bkh	Proved Undeveloped Reserve Locations ProvedUndevelopedReserveLocations	72	PUD_Location
CY2011	bkh	Public Utilities Allowance For Funds Used During Construction Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionInterestCostsCapitalized	14041000	USD
CY2010	bkh	Public Utilities Allowance For Funds Used During Construction Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionInterestCostsCapitalized	10689000	USD
CY2009	bkh	Public Utilities Allowance For Funds Used During Construction Interest Costs Capitalized PublicUtilitiesAllowanceForFundsUsedDuringConstructionInterestCostsCapitalized	5839000	USD
CY2011Q4	bkh	Pud Locations In Reserves For Five Or More Years PudLocationsInReservesForFiveOrMoreYears	0	PUD_Location
CY2011	bkh	Reserves Replaced ReservesReplaced	1.19
CY2011	bkh	Results Of Operations From Producing Activities Excluding General And Admistrative Costs And Interest Costs ResultsOfOperationsFromProducingActivitiesExcludingGeneralAndAdmistrativeCostsAndInterestCosts	14131000	USD
CY2010	bkh	Results Of Operations From Producing Activities Excluding General And Admistrative Costs And Interest Costs ResultsOfOperationsFromProducingActivitiesExcludingGeneralAndAdmistrativeCostsAndInterestCosts	15215000	USD
CY2009	bkh	Results Of Operations From Producing Activities Excluding General And Admistrative Costs And Interest Costs ResultsOfOperationsFromProducingActivitiesExcludingGeneralAndAdmistrativeCostsAndInterestCosts	-15266000	USD
CY2011	bkh	Share Based Compensation Arrangements By Share Based Payment Award Other Than Options Expected In Future Year Total Intrinsic Value ShareBasedCompensationArrangementsByShareBasedPaymentAwardOtherThanOptionsExpectedInFutureYearTotalIntrinsicValue	100000	USD
CY2010	bkh	Share Based Compensation Arrangements By Share Based Payment Awards Equity Instruments Other Than Options Vested In Period Total Intrinsic Value ShareBasedCompensationArrangementsByShareBasedPaymentAwardsEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue	0	USD
CY2009	bkh	Share Based Compensation Arrangements By Share Based Payment Awards Equity Instruments Other Than Options Vested In Period Total Intrinsic Value ShareBasedCompensationArrangementsByShareBasedPaymentAwardsEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue	0	USD
CY2009	bkh	Total Other Income Expense TotalOtherIncomeExpense	-15378000	USD
CY2010	bkh	Total Other Income Expense TotalOtherIncomeExpense	-99669000	USD
CY2011	bkh	Total Other Income Expense TotalOtherIncomeExpense	-128771000	USD
CY2011	bkh	Unrealized Gain Loss Level3 Defined Benefit Assets UnrealizedGainLossLevel3DefinedBenefitAssets	917000	USD
CY2010	bkh	Unrealized Gain Loss Level3 Defined Benefit Assets UnrealizedGainLossLevel3DefinedBenefitAssets	282000	USD
CY2011	bkh	Unregulated Energy Operating Costs UnregulatedEnergyOperatingCosts	93453000	USD
CY2010	bkh	Unregulated Energy Operating Costs UnregulatedEnergyOperatingCosts	71672000	USD
CY2009	bkh	Unregulated Energy Operating Costs UnregulatedEnergyOperatingCosts	76137000	USD
CY2011	dei	Amendment Flag AmendmentFlag	false
CY2011	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2011	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q4
CY2011	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2011
CY2011	dei	Document Period End Date DocumentPeriodEndDate	2011-12-31
CY2011	dei	Document Type DocumentType	10-K
CY2011	dei	Entity Central Index Key EntityCentralIndexKey	0001130464
CY2011Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	43929272	shares
CY2011	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2011	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2011Q2	dei	Entity Public Float EntityPublicFloat	1169775169	USD
CY2011	dei	Entity Registrant Name EntityRegistrantName	BLACK HILLS CORP /SD/
CY2011	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2011	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes

Files In Submission

Name	View Source	Status
0001130464-12-000024-index-headers.html	Edgar Link	pending
0001130464-12-000024-index.html	Edgar Link	pending
0001130464-12-000024.txt	Edgar Link	pending
0001130464-12-000024-xbrl.zip	Edgar Link	pending
bkh-20111231.xml	Edgar Link	completed
bkh-20111231.xsd	Edgar Link	pending
bkh-20111231_cal.xml	Edgar Link	unprocessable
bkh-20111231_def.xml	Edgar Link	unprocessable
bkh-20111231_lab.xml	Edgar Link	unprocessable
bkh-20111231_pre.xml	Edgar Link	unprocessable
bkh10k12312011.htm	Edgar Link	pending
bkhex-21123111.htm	Edgar Link	pending
bkhex-231122011.htm	Edgar Link	pending
bkhex-232123111.htm	Edgar Link	pending
bkhex-311122011.htm	Edgar Link	pending
bkhex-312122011.htm	Edgar Link	pending
bkhex-321122011.htm	Edgar Link	pending
bkhex-322122011.htm	Edgar Link	pending
exhibit1017amendmenttoinde.htm	Edgar Link	pending
exhibit95minesafetydata122.htm	Edgar Link	pending
exhibit99oilandgas122011.htm	Edgar Link	pending
exhitibt1010performancesha.htm	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xls	Edgar Link	pending
R1.htm	Edgar Link	pending
R10.htm	Edgar Link	pending
R100.htm	Edgar Link	pending
R101.htm	Edgar Link	pending
R102.htm	Edgar Link	pending
R103.htm	Edgar Link	pending
R104.htm	Edgar Link	pending
R105.htm	Edgar Link	pending
R106.htm	Edgar Link	pending
R107.htm	Edgar Link	pending
R108.htm	Edgar Link	pending
R109.htm	Edgar Link	pending
R11.htm	Edgar Link	pending
R110.htm	Edgar Link	pending
R111.htm	Edgar Link	pending
R112.htm	Edgar Link	pending
R113.htm	Edgar Link	pending
R114.htm	Edgar Link	pending
R115.htm	Edgar Link	pending
R116.htm	Edgar Link	pending
R117.htm	Edgar Link	pending
R118.htm	Edgar Link	pending
R119.htm	Edgar Link	pending
R12.htm	Edgar Link	pending
R120.htm	Edgar Link	pending
R121.htm	Edgar Link	pending
R122.htm	Edgar Link	pending
R123.htm	Edgar Link	pending
R124.htm	Edgar Link	pending
R125.htm	Edgar Link	pending
R126.htm	Edgar Link	pending
R127.htm	Edgar Link	pending
R128.htm	Edgar Link	pending
R129.htm	Edgar Link	pending
R13.htm	Edgar Link	pending
R130.htm	Edgar Link	pending
R131.htm	Edgar Link	pending
R132.htm	Edgar Link	pending
R133.htm	Edgar Link	pending
R134.htm	Edgar Link	pending
R135.htm	Edgar Link	pending
R136.htm	Edgar Link	pending
R137.htm	Edgar Link	pending
R138.htm	Edgar Link	pending
R139.htm	Edgar Link	pending
R14.htm	Edgar Link	pending
R140.htm	Edgar Link	pending
R141.htm	Edgar Link	pending
R142.htm	Edgar Link	pending
R143.htm	Edgar Link	pending
R144.htm	Edgar Link	pending
R145.htm	Edgar Link	pending
R146.htm	Edgar Link	pending
R147.htm	Edgar Link	pending
R148.htm	Edgar Link	pending
R149.htm	Edgar Link	pending
R15.htm	Edgar Link	pending
R150.htm	Edgar Link	pending
R16.htm	Edgar Link	pending
R17.htm	Edgar Link	pending
R18.htm	Edgar Link	pending
R19.htm	Edgar Link	pending
R2.htm	Edgar Link	pending
R20.htm	Edgar Link	pending
R21.htm	Edgar Link	pending
R22.htm	Edgar Link	pending
R23.htm	Edgar Link	pending
R24.htm	Edgar Link	pending
R25.htm	Edgar Link	pending
R26.htm	Edgar Link	pending
R27.htm	Edgar Link	pending
R28.htm	Edgar Link	pending
R29.htm	Edgar Link	pending
R3.htm	Edgar Link	pending
R30.htm	Edgar Link	pending
R31.htm	Edgar Link	pending
R32.htm	Edgar Link	pending
R33.htm	Edgar Link	pending
R34.htm	Edgar Link	pending
R35.htm	Edgar Link	pending
R36.htm	Edgar Link	pending
R37.htm	Edgar Link	pending
R38.htm	Edgar Link	pending
R39.htm	Edgar Link	pending
R4.htm	Edgar Link	pending
R40.htm	Edgar Link	pending
R41.htm	Edgar Link	pending
R42.htm	Edgar Link	pending
R43.htm	Edgar Link	pending
R44.htm	Edgar Link	pending
R45.htm	Edgar Link	pending
R46.htm	Edgar Link	pending
R47.htm	Edgar Link	pending
R48.htm	Edgar Link	pending
R49.htm	Edgar Link	pending
R5.htm	Edgar Link	pending
R50.htm	Edgar Link	pending
R51.htm	Edgar Link	pending
R52.htm	Edgar Link	pending
R53.htm	Edgar Link	pending
R54.htm	Edgar Link	pending
R55.htm	Edgar Link	pending
R56.htm	Edgar Link	pending
R57.htm	Edgar Link	pending
R58.htm	Edgar Link	pending
R59.htm	Edgar Link	pending
R6.htm	Edgar Link	pending
R60.htm	Edgar Link	pending
R61.htm	Edgar Link	pending
R62.htm	Edgar Link	pending
R63.htm	Edgar Link	pending
R64.htm	Edgar Link	pending
R65.htm	Edgar Link	pending
R66.htm	Edgar Link	pending
R67.htm	Edgar Link	pending
R68.htm	Edgar Link	pending
R69.htm	Edgar Link	pending
R7.htm	Edgar Link	pending
R70.htm	Edgar Link	pending
R71.htm	Edgar Link	pending
R72.htm	Edgar Link	pending
R73.htm	Edgar Link	pending
R74.htm	Edgar Link	pending
R75.htm	Edgar Link	pending
R76.htm	Edgar Link	pending
R77.htm	Edgar Link	pending
R78.htm	Edgar Link	pending
R79.htm	Edgar Link	pending
R8.htm	Edgar Link	pending
R80.htm	Edgar Link	pending
R81.htm	Edgar Link	pending
R82.htm	Edgar Link	pending
R83.htm	Edgar Link	pending
R84.htm	Edgar Link	pending
R85.htm	Edgar Link	pending
R86.htm	Edgar Link	pending
R87.htm	Edgar Link	pending
R88.htm	Edgar Link	pending
R89.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
R90.htm	Edgar Link	pending
R91.htm	Edgar Link	pending
R92.htm	Edgar Link	pending
R93.htm	Edgar Link	pending
R94.htm	Edgar Link	pending
R95.htm	Edgar Link	pending
R96.htm	Edgar Link	pending
R97.htm	Edgar Link	pending
R98.htm	Edgar Link	pending
R99.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending

Create your account

Find Stocks Worth Researching

Deeply Understand Businesses

Value Businesses Intelligently

$BKH
BLACK HILLS CORP /SD/ Stock $bkh

2011 Q4 Form 10-K Financial Statement

#000113046412000024 Filed on February 29, 2012

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BKH BLACK HILLS CORP /SD/ Stock $bkh

2011 Q4 Form 10-K Financial Statement

#000113046412000024 Filed on February 29, 2012

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BKH
BLACK HILLS CORP /SD/ Stock $bkh