$NWBI
Northwest Bancshares, Inc. Stock $nwbi

$nwbi Overview Financials Valuation SEC Filings Company Website

2011 Q4 Form 10-K Financial Statement

#000110465913016545 Filed on March 01, 2013

Income Statement

Concept	2011 Q4	2010 Q4	2010 Q3
Revenue	$88.54M	$93.02M	$94.01M
YoY Change	-4.82%
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	$900.0K	$4.000M	$3.700M
YoY Change	-77.5%	-4.76%	-11.9%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$22.27M	$25.79M	$27.36M
YoY Change	-13.65%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$21.64M	$17.78M	$21.56M
YoY Change	21.69%	-622.97%	34.74%
Income Tax	$6.463M	$5.043M	$6.068M
% Of Pretax Income	29.87%	28.36%	28.15%
Net Earnings	$15.20M	$12.70M	$15.50M
YoY Change	19.69%	1170.0%	28.1%
Net Earnings / Revenue	17.17%	13.65%	16.49%
Basic Earnings Per Share	$0.16	$0.12	$0.14
Diluted Earnings Per Share	$0.16	$0.12	$0.14
COMMON SHARES
Basic Shares Outstanding
Diluted Shares Outstanding

Balance Sheet

Concept	2011 Q4	2010 Q4	2010 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$688.3M	$719.1M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$132.2M	$128.1M	$127.0M
YoY Change	3.16%	3.31%	2.42%
Goodwill	$171.9M	$171.9M
YoY Change	0.0%
Intangibles	$2.123M	$3.942M
YoY Change	-46.14%
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$7.958B	$8.148B	$8.143B
YoY Change	-2.34%	1.53%	14.18%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$1.000M	$2.000M	$2.000M
YoY Change	-50.0%	-50.0%	-60.0%
Accrued Expenses
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$828.0M	$891.0M	$876.0M
YoY Change	-7.07%	674.78%	742.31%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$1.000M	$2.000M	$2.000M
YoY Change	-50.0%	-50.0%	-60.0%
LONG-TERM LIABILITIES
Long-Term Debt	$103.0M	$103.0M	$103.0M
YoY Change	0.0%	0.0%	0.0%
Other Long-Term Liabilities	$67.00M	$57.00M	$65.00M
YoY Change	17.54%	0.0%	-12.16%
Total Long-Term Liabilities	$170.0M	$160.0M	$168.0M
YoY Change	6.25%	0.0%	-5.08%
TOTAL LIABILITIES
Total Short-Term Liabilities	$1.000M	$2.000M	$2.000M
Total Long-Term Liabilities	$170.0M	$160.0M	$168.0M
Total Liabilities	$6.803B	$6.841B	$6.828B
YoY Change	-0.55%	1.96%	5.39%
SHAREHOLDERS EQUITY
Retained Earnings	$543.6M	$523.1M
YoY Change	3.92%
Common Stock	$660.5M	$1.103M
YoY Change	59781.96%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$1.155B	$1.307B	$1.315B
YoY Change
Total Liabilities & Shareholders Equity	$7.958B	$8.148B	$8.143B
YoY Change	-2.34%	1.53%	14.18%

Cashflow Statement

Concept	2011 Q4	2010 Q4	2010 Q3
OPERATING ACTIVITIES
Net Income	$15.20M	$12.70M	$15.50M
YoY Change	19.69%	1170.0%	28.1%
Depreciation, Depletion And Amortization	$900.0K	$4.000M	$3.700M
YoY Change	-77.5%	-4.76%	-11.9%
Cash From Operating Activities	$5.900M	$44.20M	-$19.30M
YoY Change	-86.65%	-1573.33%	-176.59%
INVESTING ACTIVITIES
Capital Expenditures	-$8.000M	-$4.200M	-$4.000M
YoY Change	90.48%	16.67%	-39.39%
Acquisitions
YoY Change
Other Investing Activities	$52.70M	-$1.200M	-$97.60M
YoY Change	-4491.67%	-96.49%	-42.28%
Cash From Investing Activities	$44.80M	-$5.400M	-$101.6M
YoY Change	-929.63%	-85.71%	-42.17%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-33.40M	4.500M	-10.40M
YoY Change	-842.22%	-99.48%	-166.67%
NET CHANGE
Cash From Operating Activities	5.900M	44.20M	-19.30M
Cash From Investing Activities	44.80M	-5.400M	-101.6M
Cash From Financing Activities	-33.40M	4.500M	-10.40M
Net Change In Cash	17.30M	43.30M	-131.3M
YoY Change	-60.05%	-94.77%	-2.67%
FREE CASH FLOW
Cash From Operating Activities	$5.900M	$44.20M	-$19.30M
Capital Expenditures	-$8.000M	-$4.200M	-$4.000M
Free Cash Flow	$13.90M	$48.40M	-$15.30M
YoY Change	-71.28%	7966.67%	-148.11%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2012Q4	us-gaap	Cash And Due From Banks CashAndDueFromBanks	88277000	USD
CY2012Q4	us-gaap	Interest Bearing Deposits In Banks InterestBearingDepositsInBanks	362794000	USD
CY2012Q4	nwbi	Federal Funds Sold And Other Short Term Investments FederalFundsSoldAndOtherShortTermInvestments	633000	USD
CY2012Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	1079074000	USD
CY2012Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	155081000	USD
CY2012Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	5629261000	USD
CY2011	us-gaap	Interest Expense InterestExpense	92801000	USD
CY2011	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	7101000	USD
CY2011	us-gaap	Other Noninterest Expense OtherNoninterestExpense	8673000	USD
CY2012Q4	us-gaap	Interest Receivable InterestReceivable	23313000	USD
CY2012Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	26165000	USD
CY2012Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	46834000	USD
CY2012Q4	us-gaap	Stockholders Equity StockholdersEquity	1128469000	USD
CY2012Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	138824000	USD
CY2012Q4	us-gaap	Bank Owned Life Insurance BankOwnedLifeInsurance	137044000	USD
CY2012Q4	us-gaap	Goodwill Goodwill	174461000	USD
CY2012Q4	us-gaap	Other Assets OtherAssets	77310000	USD
CY2012Q4	us-gaap	Assets Assets	7942600000	USD
CY2012Q4	us-gaap	Deposits Deposits	5764600000	USD
CY2012Q4	us-gaap	Borrowed Funds BorrowedFunds	860047000	USD
CY2012Q4	us-gaap	Advance Payments By Borrowers For Taxes And Insurance AdvancePaymentsByBorrowersForTaxesAndInsurance	23325000	USD
CY2012Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	888000	USD
CY2012Q4	us-gaap	Other Liabilities OtherLiabilities	62177000	USD
CY2012Q4	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	103094000	USD
CY2012Q4	us-gaap	Liabilities Liabilities	6814131000	USD
CY2011Q4	us-gaap	Preferred Stock Value PreferredStockValue		USD
CY2012Q4	us-gaap	Preferred Stock Value PreferredStockValue		USD
CY2012Q4	us-gaap	Common Stock Value CommonStockValue	937000	USD
CY2012Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	613249000	USD
CY2012Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	550296000	USD
CY2012Q4	nwbi	Unallocated Common Stock Held By Esop UnallocatedCommonStockHeldByESOP	24525000	USD
CY2012Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-11488000	USD
CY2012Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	7942600000	USD
CY2011Q4	us-gaap	Cash And Due From Banks CashAndDueFromBanks	94276000	USD
CY2011Q4	us-gaap	Interest Bearing Deposits In Banks InterestBearingDepositsInBanks	593388000	USD
CY2011Q4	nwbi	Federal Funds Sold And Other Short Term Investments FederalFundsSoldAndOtherShortTermInvestments	633000	USD
CY2011Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	908349000	USD
CY2011Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	231389000	USD
CY2011Q4	us-gaap	Loans And Leases Receivable Net Reported Amount LoansAndLeasesReceivableNetReportedAmount	5480381000	USD
CY2011Q4	us-gaap	Interest Receivable InterestReceivable	24599000	USD
CY2011Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	26887000	USD
CY2011Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	48935000	USD
CY2011Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	132152000	USD
CY2011Q4	us-gaap	Bank Owned Life Insurance BankOwnedLifeInsurance	133524000	USD
CY2011Q4	us-gaap	Goodwill Goodwill	171882000	USD
CY2011Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	2123000	USD
CY2012	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	2029000	USD
CY2011Q4	us-gaap	Other Assets OtherAssets	109187000	USD
CY2011Q4	us-gaap	Assets Assets	7957705000	USD
CY2011Q4	us-gaap	Deposits Deposits	5780325000	USD
CY2011Q4	us-gaap	Borrowed Funds BorrowedFunds	827925000	USD
CY2011Q4	us-gaap	Advance Payments By Borrowers For Taxes And Insurance AdvancePaymentsByBorrowersForTaxesAndInsurance	23571000	USD
CY2011Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	1104000	USD
CY2011Q4	us-gaap	Other Liabilities OtherLiabilities	66782000	USD
CY2011Q4	us-gaap	Junior Subordinated Debenture Owed To Unconsolidated Subsidiary Trust JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrust	103094000	USD
CY2011Q4	us-gaap	Liabilities Liabilities	6802801000	USD
CY2011Q4	us-gaap	Common Stock Value CommonStockValue	975000	USD
CY2011Q4	us-gaap	Additional Paid In Capital Common Stock AdditionalPaidInCapitalCommonStock	659523000	USD
CY2011Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	543598000	USD
CY2011Q4	nwbi	Unallocated Common Stock Held By Esop UnallocatedCommonStockHeldByESOP	25966000	USD
CY2011Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-23226000	USD
CY2011Q4	us-gaap	Stockholders Equity StockholdersEquity	1154904000	USD
CY2011Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	7957705000	USD
CY2012Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2011Q4	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2012Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	50000000	shares
CY2012Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2012Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2011Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2012Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2012Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	93652960	shares
CY2011Q4	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	50000000	shares
CY2011Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2011Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	500000000	shares
CY2011Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	97493046	shares
CY2012Q4	nwbi	Loans And Leases Receivable Allowance Including Unallocated LoansAndLeasesReceivableAllowanceIncludingUnallocated	73219000	USD
CY2011Q4	nwbi	Loans And Leases Receivable Allowance Including Unallocated LoansAndLeasesReceivableAllowanceIncludingUnallocated	71138000	USD
CY2012	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	309391000	USD
CY2012	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	16738000	USD
CY2012	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	2328000	USD
CY2012	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	9119000	USD
CY2012	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	1599000	USD
CY2012	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	339175000	USD
CY2012	us-gaap	Interest Expense Deposits InterestExpenseDeposits	43377000	USD
CY2012	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	31822000	USD
CY2012	us-gaap	Interest Expense InterestExpense	75199000	USD
CY2012	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	263976000	USD
CY2012	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	26338000	USD
CY2012	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	237638000	USD
CY2012	us-gaap	Impairment Of Investments ImpairmentOfInvestments	996000	USD
CY2012	nwbi	Noncredit Related Losses On Securities Not Expected To Be Sold NoncreditRelatedLossesOnSecuritiesNotExpectedToBeSold	665000	USD
CY2012	nwbi	Net Other Than Temporary Impairments NetOtherThanTemporaryImpairments	331000	USD
CY2012	us-gaap	Gain Loss On Sale Of Securities Net GainLossOnSaleOfSecuritiesNet	654000	USD
CY2012	us-gaap	Fees And Commissions Depositor Accounts FeesAndCommissionsDepositorAccounts	34486000	USD
CY2012	us-gaap	Fees And Commissions Fiduciary And Trust Activities FeesAndCommissionsFiduciaryAndTrustActivities	8544000	USD
CY2012	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	6264000	USD
CY2012	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-5643000	USD
CY2012	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	4961000	USD
CY2012	nwbi	Mortgage Banking Income MortgageBankingIncome	4678000	USD
CY2012	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	4154000	USD
CY2012	us-gaap	Noninterest Income NoninterestIncome	57767000	USD
CY2012	us-gaap	Labor And Related Expense LaborAndRelatedExpense	111727000	USD
CY2012	us-gaap	Occupancy Costs OccupancyCosts	22409000	USD
CY2012	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13224000	USD
CY2012	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	25000000	USD
CY2012	us-gaap	Professional Fees ProfessionalFees	7005000	USD
CY2012	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1012000	USD
CY2012	us-gaap	Marketing Expense MarketingExpense	7829000	USD
CY2012	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	2620000	USD
CY2012	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	5554000	USD
CY2012	us-gaap	Other Noninterest Expense OtherNoninterestExpense	9074000	USD
CY2012	us-gaap	Noninterest Expense NoninterestExpense	205477000	USD
CY2012	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	89928000	USD
CY2012	nwbi	Federal Tax Expense Benefit FederalTaxExpenseBenefit	22484000	USD
CY2012	nwbi	State And Local Tax Expense Benefit StateAndLocalTaxExpenseBenefit	3884000	USD
CY2012	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	26368000	USD
CY2012	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.68
CY2012	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.68
CY2011	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	320942000	USD
CY2011	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	23450000	USD
CY2011	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	2452000	USD
CY2011	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	11514000	USD
CY2011	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	1712000	USD
CY2011	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	360070000	USD
CY2011	us-gaap	Interest Expense Deposits InterestExpenseDeposits	60721000	USD
CY2011	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	32080000	USD
CY2011	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	267269000	USD
CY2011	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	34170000	USD
CY2011	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	233099000	USD
CY2011	us-gaap	Impairment Of Investments ImpairmentOfInvestments	2081000	USD
CY2011	nwbi	Noncredit Related Losses On Securities Not Expected To Be Sold NoncreditRelatedLossesOnSecuritiesNotExpectedToBeSold	1144000	USD
CY2011	nwbi	Net Other Than Temporary Impairments NetOtherThanTemporaryImpairments	937000	USD
CY2011	us-gaap	Gain Loss On Sale Of Securities Net GainLossOnSaleOfSecuritiesNet	358000	USD
CY2011	us-gaap	Fees And Commissions Depositor Accounts FeesAndCommissionsDepositorAccounts	35378000	USD
CY2011	us-gaap	Fees And Commissions Fiduciary And Trust Activities FeesAndCommissionsFiduciaryAndTrustActivities	8125000	USD
CY2011	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	6548000	USD
CY2011	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-2426000	USD
CY2011	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	6019000	USD
CY2011	nwbi	Mortgage Banking Income MortgageBankingIncome	858000	USD
CY2011	us-gaap	Labor And Related Expense LaborAndRelatedExpense	106595000	USD
CY2011	us-gaap	Noninterest Income NoninterestIncome	58136000	USD
CY2011	us-gaap	Occupancy Costs OccupancyCosts	23055000	USD
CY2011	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	12850000	USD
CY2011	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	23332000	USD
CY2011	us-gaap	Professional Fees ProfessionalFees	5224000	USD
CY2011	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	1819000	USD
CY2011	us-gaap	Marketing Expense MarketingExpense	9953000	USD
CY2011	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	1625000	USD
CY2011	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	91008000	USD
CY2011	us-gaap	Noninterest Expense NoninterestExpense	200227000	USD
CY2011	nwbi	Federal Tax Expense Benefit FederalTaxExpenseBenefit	22623000	USD
CY2011	nwbi	State And Local Tax Expense Benefit StateAndLocalTaxExpenseBenefit	4234000	USD
CY2011	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	26857000	USD
CY2011	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	64151000	USD
CY2011	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.64
CY2011	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.64
CY2010	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	328948000	USD
CY2010	us-gaap	Interest Income Securities Mortgage Backed InterestIncomeSecuritiesMortgageBacked	25271000	USD
CY2010	us-gaap	Interest Income Securities Taxable InterestIncomeSecuritiesTaxable	2514000	USD
CY2010	us-gaap	Interest Income Securities Tax Exempt InterestIncomeSecuritiesTaxExempt	11738000	USD
CY2010	us-gaap	Interest Income Deposits With Financial Institutions InterestIncomeDepositsWithFinancialInstitutions	2097000	USD
CY2010	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	370568000	USD
CY2010	us-gaap	Interest Expense Deposits InterestExpenseDeposits	75174000	USD
CY2010	us-gaap	Interest Expense Borrowings InterestExpenseBorrowings	37753000	USD
CY2010	us-gaap	Interest Expense InterestExpense	112927000	USD
CY2010	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	257641000	USD
CY2010	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	40486000	USD
CY2010	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	217155000	USD
CY2010	us-gaap	Impairment Of Investments ImpairmentOfInvestments	2734000	USD
CY2010	nwbi	Noncredit Related Losses On Securities Not Expected To Be Sold NoncreditRelatedLossesOnSecuritiesNotExpectedToBeSold	1193000	USD
CY2010	nwbi	Net Other Than Temporary Impairments NetOtherThanTemporaryImpairments	1541000	USD
CY2010	us-gaap	Gain Loss On Sale Of Securities Net GainLossOnSaleOfSecuritiesNet	2201000	USD
CY2010	us-gaap	Fees And Commissions Depositor Accounts FeesAndCommissionsDepositorAccounts	37921000	USD
CY2010	us-gaap	Fees And Commissions Fiduciary And Trust Activities FeesAndCommissionsFiduciaryAndTrustActivities	7252000	USD
CY2010	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	5190000	USD
CY2010	us-gaap	Gains Losses On Sales Of Other Real Estate GainsLossesOnSalesOfOtherRealEstate	-2572000	USD
CY2010	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	5080000	USD
CY2010	nwbi	Mortgage Banking Income MortgageBankingIncome	2196000	USD
CY2010	us-gaap	Noninterest Income NoninterestIncome	60398000	USD
CY2011	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	4213000	USD
CY2010	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	4671000	USD
CY2010	us-gaap	Labor And Related Expense LaborAndRelatedExpense	100709000	USD
CY2010	us-gaap	Occupancy Costs OccupancyCosts	22665000	USD
CY2010	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13864000	USD
CY2010	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	23152000	USD
CY2010	us-gaap	Professional Fees ProfessionalFees	2728000	USD
CY2010	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	2784000	USD
CY2010	us-gaap	Marketing Expense MarketingExpense	9875000	USD
CY2010	us-gaap	Foreclosed Real Estate Expense ForeclosedRealEstateExpense	2901000	USD
CY2010	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	9054000	USD
CY2010	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	1229000	USD
CY2010	us-gaap	Other Noninterest Expense OtherNoninterestExpense	7547000	USD
CY2010	us-gaap	Noninterest Expense NoninterestExpense	196508000	USD
CY2010	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	81045000	USD
CY2010	nwbi	Federal Tax Expense Benefit FederalTaxExpenseBenefit	20267000	USD
CY2010	nwbi	State And Local Tax Expense Benefit StateAndLocalTaxExpenseBenefit	3255000	USD
CY2010	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	23522000	USD
CY2010	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	57523000	USD
CY2010	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.53
CY2010	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.53
CY2011	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	9312000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment For Write Down Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForWriteDownOfSecuritiesIncludedInNetIncomeNetOfTax	-609000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeNetOfTax	-1104000	USD
CY2011	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	11025000	USD
CY2011	us-gaap	Other Comprehensive Income Derivatives Qualifying As Hedges Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDerivativesQualifyingAsHedgesNetOfTaxPortionAttributableToParent	-2787000	USD
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	-17863000	USD
CY2011	us-gaap	Other Comprehensive Income Amortization Of Defined Benefit Plan Net Prior Service Cost Recognized In Net Periodic Pension Cost Net Of Tax OtherComprehensiveIncomeAmortizationOfDefinedBenefitPlanNetPriorServiceCostRecognizedInNetPeriodicPensionCostNetOfTax	-104000	USD
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	17967000	USD
CY2011	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-9729000	USD
CY2011	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	54422000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-1975000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment For Write Down Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForWriteDownOfSecuritiesIncludedInNetIncomeNetOfTax	-1002000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeNetOfTax	878000	USD
CY2010	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	-1851000	USD
CY2010	us-gaap	Other Comprehensive Income Derivatives Qualifying As Hedges Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDerivativesQualifyingAsHedgesNetOfTaxPortionAttributableToParent	-2855000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	1290000	USD
CY2010	us-gaap	Other Comprehensive Income Amortization Of Defined Benefit Plan Net Prior Service Cost Recognized In Net Periodic Pension Cost Net Of Tax OtherComprehensiveIncomeAmortizationOfDefinedBenefitPlanNetPriorServiceCostRecognizedInNetPeriodicPensionCostNetOfTax	-104000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	-1186000	USD
CY2012	us-gaap	Other Comprehensive Income Reclassification Adjustment For Write Down Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForWriteDownOfSecuritiesIncludedInNetIncomeNetOfTax	-202000	USD
CY2010	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-3520000	USD
CY2010	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	54003000	USD
CY2012	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	1807000	USD
CY2012	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	-9472000	USD
CY2012	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	1346000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	5996000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-1239000	USD
CY2012	us-gaap	Other Comprehensive Income Reclassification Adjustment For Write Down Of Securities Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentForWriteDownOfSecuritiesIncludedInNetIncomeTax	-129000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment For Write Down Of Securities Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentForWriteDownOfSecuritiesIncludedInNetIncomeTax	-328000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment For Write Down Of Securities Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentForWriteDownOfSecuritiesIncludedInNetIncomeTax	-539000	USD
CY2012	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeTax	271000	USD
CY2011	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeTax	-705000	USD
CY2010	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeTax	473000	USD
CY2012	us-gaap	Other Comprehensive Income Derivatives Qualifying As Hedges Tax Portion Attributable To Parent OtherComprehensiveIncomeDerivativesQualifyingAsHedgesTaxPortionAttributableToParent	246000	USD
CY2011	us-gaap	Other Comprehensive Income Derivatives Qualifying As Hedges Tax Portion Attributable To Parent OtherComprehensiveIncomeDerivativesQualifyingAsHedgesTaxPortionAttributableToParent	-1506000	USD
CY2010	us-gaap	Other Comprehensive Income Derivatives Qualifying As Hedges Tax Portion Attributable To Parent OtherComprehensiveIncomeDerivativesQualifyingAsHedgesTaxPortionAttributableToParent	-1534000	USD
CY2012	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-6112000	USD
CY2012	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent OtherComprehensiveIncomeLossTaxPortionAttributableToParent	-7506000	USD
CY2011	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent OtherComprehensiveIncomeLossTaxPortionAttributableToParent	5964000	USD
CY2010	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.40
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	11431000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax	-814000	USD
CY2012	us-gaap	Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans Net Prior Service Cost Recognized In Net Periodic Pension Cost Tax Effect OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostRecognizedInNetPeriodicPensionCostTaxEffect	56000	USD
CY2011	us-gaap	Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans Net Prior Service Cost Recognized In Net Periodic Pension Cost Tax Effect OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostRecognizedInNetPeriodicPensionCostTaxEffect	56000	USD
CY2010	us-gaap	Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans Net Prior Service Cost Recognized In Net Periodic Pension Cost Tax Effect OtherComprehensiveIncomeLossAmortizationPensionAndOtherPostretirementBenefitPlansNetPriorServiceCostRecognizedInNetPeriodicPensionCostTaxEffect	56000	USD
CY2009Q4	us-gaap	Stockholders Equity StockholdersEquity	1316515000	USD
CY2010	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	1599000	USD
CY2010	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	2237000	USD
CY2010	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	6428000	USD
CY2010	us-gaap	Dividends Cash DividendsCash	43276000	USD
CY2010	us-gaap	Stock Repurchased During Period Value StockRepurchasedDuringPeriodValue	17200000	USD
CY2010Q4	us-gaap	Stockholders Equity StockholdersEquity	1307450000	USD
CY2011	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	2030000	USD
CY2011	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	7334000	USD
CY2011	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	172690000	USD
CY2011	us-gaap	Dividends Cash DividendsCash	43642000	USD
CY2012	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	5026000	USD
CY2012	us-gaap	Dividends Cash DividendsCash	56862000	USD
CY2012	us-gaap	Stock Repurchased And Retired During Period Value StockRepurchasedAndRetiredDuringPeriodValue	52028000	USD
CY2010	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent OtherComprehensiveIncomeLossTaxPortionAttributableToParent	1949000	USD
CY2012	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.60
CY2011	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.43
CY2012	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	2894000	USD
CY2011	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	-2999000	USD
CY2010	us-gaap	Gains Losses On Sales Of Assets GainsLossesOnSalesOfAssets	-810000	USD
CY2012	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	9466000	USD
CY2011	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	7790000	USD
CY2010	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	14771000	USD
CY2012	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-18695000	USD
CY2011	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-7534000	USD
CY2010	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-11060000	USD
CY2012	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	11351000	USD
CY2011	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-24967000	USD
CY2010	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-5241000	USD
CY2012	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	76000	USD
CY2011	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	186000	USD
CY2010	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	130000	USD
CY2012	us-gaap	Share Based Compensation ShareBasedCompensation	4623000	USD
CY2011	us-gaap	Share Based Compensation ShareBasedCompensation	6725000	USD
CY2010	us-gaap	Share Based Compensation ShareBasedCompensation	2237000	USD
CY2012	us-gaap	Unrealized Gain Loss On Securities UnrealizedGainLossOnSecurities	-331000	USD
CY2011	us-gaap	Unrealized Gain Loss On Securities UnrealizedGainLossOnSecurities	-937000	USD
CY2010	us-gaap	Unrealized Gain Loss On Securities UnrealizedGainLossOnSecurities	-1541000	USD
CY2012	us-gaap	Impairment Of Real Estate ImpairmentOfRealEstate	4942000	USD
CY2011	us-gaap	Impairment Of Real Estate ImpairmentOfRealEstate	1449000	USD
CY2010	us-gaap	Impairment Of Real Estate ImpairmentOfRealEstate	1338000	USD
CY2010	us-gaap	Mortgage Servicing Rights Msr Impairment Recovery MortgageServicingRightsMSRImpairmentRecovery	-505000	USD
CY2010	nwbi	Federal Home Loan Bank Prepayment Penalty FederalHomeLoanBankPrepaymentPenalty	52016000	USD
CY2012	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	3295000	USD
CY2011	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	7749000	USD
CY2010	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	431000	USD
CY2012	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	248658000	USD
CY2011	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	77887000	USD
CY2010	us-gaap	Payments For Origination And Purchases Of Loans Held For Sale PaymentsForOriginationAndPurchasesOfLoansHeldForSale	207272000	USD
CY2012	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	236482000	USD
CY2011	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	88238000	USD
CY2010	us-gaap	Proceeds From Sale Of Loans Held For Sale ProceedsFromSaleOfLoansHeldForSale	205310000	USD
CY2012	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	127455000	USD
CY2011	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	118702000	USD
CY2010	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	70343000	USD
CY2010	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	485995000	USD
CY2012	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	508553000	USD
CY2011	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	237058000	USD
CY2010	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	296576000	USD
CY2012	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	76257000	USD
CY2011	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	126012000	USD
CY2010	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	126766000	USD
CY2012	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	341287000	USD
CY2011	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	297348000	USD
CY2010	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	355195000	USD
CY2010	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	56865000	USD
CY2012	nwbi	Originations Of Loans Receivable Held For Investment OriginationsOfLoansReceivableHeldForInvestment	2088565000	USD
CY2011	nwbi	Originations Of Loans Receivable Held For Investment OriginationsOfLoansReceivableHeldForInvestment	1850368000	USD
CY2010	nwbi	Originations Of Loans Receivable Held For Investment OriginationsOfLoansReceivableHeldForInvestment	1929914000	USD
CY2012	us-gaap	Proceeds From Principal Repayments On Loans And Leases Held For Investment ProceedsFromPrincipalRepaymentsOnLoansAndLeasesHeldForInvestment	1911871000	USD
CY2011	us-gaap	Proceeds From Principal Repayments On Loans And Leases Held For Investment ProceedsFromPrincipalRepaymentsOnLoansAndLeasesHeldForInvestment	1766191000	USD
CY2010	us-gaap	Proceeds From Principal Repayments On Loans And Leases Held For Investment ProceedsFromPrincipalRepaymentsOnLoansAndLeasesHeldForInvestment	1648005000	USD
CY2012	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	-2101000	USD
CY2011	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	-11145000	USD
CY2010	us-gaap	Payments For Proceeds From Federal Home Loan Bank Stock PaymentsForProceedsFromFederalHomeLoanBankStock	-3162000	USD
CY2012	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	14049000	USD
CY2011	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	10648000	USD
CY2010	us-gaap	Proceeds From Sale Of Foreclosed Assets ProceedsFromSaleOfForeclosedAssets	12026000	USD
CY2012	us-gaap	Payments To Acquire Real Estate Held For Investment PaymentsToAcquireRealEstateHeldForInvestment	-457000	USD
CY2011	us-gaap	Payments To Acquire Real Estate Held For Investment PaymentsToAcquireRealEstateHeldForInvestment	22000	USD
CY2010	us-gaap	Payments To Acquire Real Estate Held For Investment PaymentsToAcquireRealEstateHeldForInvestment	2030000	USD
CY2012	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	18255000	USD
CY2011	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	12434000	USD
CY2010	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	15940000	USD
CY2012	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-273440000	USD
CY2011	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	111462000	USD
CY2010	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-528436000	USD
CY2012	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	4089000	USD
CY2012	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	-15725000	USD
CY2011	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	15989000	USD
CY2010	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	139912000	USD
CY2012	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	69000	USD
CY2011	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	50066000	USD
CY2010	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	36564000	USD
CY2012	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	32191000	USD
CY2011	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-13302000	USD
CY2010	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	30537000	USD
CY2012	nwbi	Increase Decrease In Advances By Borrowers For Taxes And Insurance IncreaseDecreaseInAdvancesByBorrowersForTaxesAndInsurance	-246000	USD
CY2011	nwbi	Increase Decrease In Advances By Borrowers For Taxes And Insurance IncreaseDecreaseInAdvancesByBorrowersForTaxesAndInsurance	703000	USD
CY2010	nwbi	Increase Decrease In Advances By Borrowers For Taxes And Insurance IncreaseDecreaseInAdvancesByBorrowersForTaxesAndInsurance	834000	USD
CY2012	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	52028000	USD
CY2011	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	172690000	USD
CY2010	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	6428000	USD
CY2012	us-gaap	Payments Of Dividends PaymentsOfDividends	56862000	USD
CY2011	us-gaap	Payments Of Dividends PaymentsOfDividends	43642000	USD
CY2010	us-gaap	Payments Of Dividends PaymentsOfDividends	43276000	USD
CY2010	nwbi	Purchase Of Common Stock For Employee Stock Ownership Plan PurchaseOfCommonStockForEmployeeStockOwnershipPlan	17200000	USD
CY2012	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	2131000	USD
CY2011	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	2030000	USD
CY2010	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	1599000	USD
CY2012	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	-90608000	USD
CY2011	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	-260978000	USD
CY2010	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	69414000	USD
CY2012	us-gaap	Net Cash Provided By Used In Continuing Operations NetCashProvidedByUsedInContinuingOperations	-236593000	USD
CY2011	us-gaap	Net Cash Provided By Used In Continuing Operations NetCashProvidedByUsedInContinuingOperations	-30814000	USD
CY2010	us-gaap	Net Cash Provided By Used In Continuing Operations NetCashProvidedByUsedInContinuingOperations	-388679000	USD
CY2010Q4	us-gaap	Cash And Due From Banks CashAndDueFromBanks	40708000	USD
CY2010Q4	us-gaap	Interest Bearing Deposits In Banks InterestBearingDepositsInBanks	677771000	USD
CY2010Q4	nwbi	Federal Funds Sold And Other Short Term Investments FederalFundsSoldAndOtherShortTermInvestments	632000	USD
CY2010Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	719111000	USD
CY2012Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	451704000	USD
CY2011Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	688297000	USD
CY2012	nwbi	Cash Paid For Interest On Deposits And Borrowings CashPaidForInterestOnDepositsAndBorrowings	75415000	USD
CY2011	nwbi	Cash Paid For Interest On Deposits And Borrowings CashPaidForInterestOnDepositsAndBorrowings	93413000	USD
CY2010	nwbi	Cash Paid For Interest On Deposits And Borrowings CashPaidForInterestOnDepositsAndBorrowings	115704000	USD
CY2012	us-gaap	Income Taxes Paid IncomeTaxesPaid	14278000	USD
CY2011	us-gaap	Income Taxes Paid IncomeTaxesPaid	23916000	USD
CY2010	us-gaap	Income Taxes Paid IncomeTaxesPaid	19715000	USD
CY2012	nwbi	Transfer Of Other Real Estate And Other Repossessed Personal Property TransferOfOtherRealEstateAndOtherRepossessedPersonalProperty	20080000	USD
CY2011	nwbi	Transfer Of Other Real Estate And Other Repossessed Personal Property TransferOfOtherRealEstateAndOtherRepossessedPersonalProperty	20410000	USD
CY2010	nwbi	Transfer Of Other Real Estate And Other Repossessed Personal Property TransferOfOtherRealEstateAndOtherRepossessedPersonalProperty	16535000	USD
CY2012	nwbi	Sale And Financing Of Other Real Estate Owned SaleAndFinancingOfOtherRealEstateOwned	461000	USD
CY2011	nwbi	Sale And Financing Of Other Real Estate Owned SaleAndFinancingOfOtherRealEstateOwned	379000	USD
CY2010	nwbi	Sale And Financing Of Other Real Estate Owned SaleAndFinancingOfOtherRealEstateOwned	1348000	USD
CY2012	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	4152000	USD
CY2012	us-gaap	Cash Acquired From Acquisition CashAcquiredFromAcquisition	-4089000	USD
CY2012	us-gaap	Noncash Or Part Noncash Acquisition Value Of Liabilities Assumed1 NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1	63000	USD
CY2009Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	1107790000	USD
CY2012	nwbi	Cash Paid For Interest On Deposits CashPaidForInterestOnDeposits	37633000	USD
CY2011	nwbi	Cash Paid For Interest On Deposits CashPaidForInterestOnDeposits	51591000	USD
CY2010	nwbi	Cash Paid For Interest On Deposits CashPaidForInterestOnDeposits	65481000	USD
CY2012	dei	Entity Registrant Name EntityRegistrantName	Northwest Bancshares, Inc.
CY2012	dei	Entity Central Index Key EntityCentralIndexKey	0001471265
CY2012	dei	Document Type DocumentType	10-K
CY2012	dei	Document Period End Date DocumentPeriodEndDate	2012-12-31
CY2012	dei	Amendment Flag AmendmentFlag	false
CY2012	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2012	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2012	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2012	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2012	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2012	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2012
CY2012	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2012	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	63560000	USD
CY2011Q4	us-gaap	Available For Sale Securities Fair Value Disclosure AvailableForSaleSecuritiesFairValueDisclosure	908349000	USD
CY2011Q4	us-gaap	Availableforsale Securities Gross Unrealized Gain AvailableforsaleSecuritiesGrossUnrealizedGain	29151000	USD
CY2011Q4	us-gaap	Available For Sale Securities Gross Unrealized Losses1 AvailableForSaleSecuritiesGrossUnrealizedLosses1	6210000	USD
CY2012	us-gaap	Use Of Estimates UseOfEstimates	<div style='font-size:10.0pt;FONT-FAMILY: Times New Roman;'> <p style="MARGIN: 0in 0in 0pt 0.5in"><b><i><font style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-STYLE: italic; FONT-FAMILY: Times New Roman" size="2">(s)</font></i></b><b><i><font style="FONT-WEIGHT: bold; FONT-SIZE: 3pt; FONT-STYLE: italic" size="1">                                  </font></i></b> <b><i><font style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-STYLE: italic" size="2">Use of Estimates</font></i></b></p> <p style="MARGIN: 0in 0in 0pt 0.5in"><font style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman" size="2"> </font></p> <p style="MARGIN: 0in 0in 0pt; TEXT-INDENT: 0.5in"><font style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman" size="2">The preparation of financial statements, in conformity with accounting principles generally accepted in the United States of America, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amount of revenues and expenses during the reporting period. The estimates and assumptions that we deem important to our financial statements relate to the allowance for loan losses, the accounting treatment and valuation of our investment securities portfolio, the analysis of the carrying value of goodwill and income taxes.  These estimates and assumptions are based on management’s best estimates and judgment and we evaluate them using historical experience and other factors, including the current economic environment.  We adjust our estimates and assumptions when facts and circumstances dictate.  As future events cannot be determined, actual results could differ significantly from our estimates.</font></p></div>
CY2012	us-gaap	Comparability Of Prior Year Financial Data ComparabilityOfPriorYearFinancialData	<div style='font-size:10.0pt;FONT-FAMILY: Times New Roman;'> <p style="MARGIN: 0in 0in 0pt 0.5in"><b><i><font style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-STYLE: italic; FONT-FAMILY: Times New Roman" size="2">(t)</font></i></b><b><i><font style="FONT-WEIGHT: bold; FONT-SIZE: 3pt; FONT-STYLE: italic" size="1">                                   </font></i></b> <b><i><font style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-STYLE: italic" size="2">Reclassification of Prior Years’ Statements</font></i></b></p> <p style="MARGIN: 0in 0in 0pt 0.5in"><font style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman" size="2"> </font></p> <p style="MARGIN: 0in 0in 0pt; TEXT-INDENT: 0.5in"><font style="FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman" size="2">Certain items previously reported have been reclassified to conform with the current year’s reporting format.</font></p></div>
CY2012Q4	nwbi	Number Of Banking Locations NumberOfBankingLocations	165	item
CY2012Q4	nwbi	Number Of Consumer Finance Offices NumberOfConsumerFinanceOffices	52	item
CY2012	nwbi	Maximum Term Of Original Maturity To Classify Instruments As Cash And Cash Equivalents MaximumTermOfOriginalMaturityToClassifyInstrumentsAsCashAndCashEquivalents	3
CY2012	nwbi	Period To Return Troubled Debt Restructured Loans Included In Non Performing Loans To Performing Status PeriodToReturnTroubledDebtRestructuredLoansIncludedInNonPerformingLoansToPerformingStatus	6
CY2011Q4	us-gaap	Loans Held For Sale Mortgages LoansHeldForSaleMortgages	967000	USD
CY2012Q4	us-gaap	Loans Held For Sale Mortgages LoansHeldForSaleMortgages	15400000	USD
CY2012	us-gaap	Property Plant And Equipment Useful Life Minimum PropertyPlantAndEquipmentUsefulLifeMinimum	3
CY2012	us-gaap	Property Plant And Equipment Useful Life Maximum PropertyPlantAndEquipmentUsefulLifeMaximum	39
CY2012	nwbi	Goodwill Impaired Number Of Valuation Methodologies GoodwillImpairedNumberOfValuationMethodologies	4	methodology
CY2012	us-gaap	Finite Lived Intangible Assets Useful Life FiniteLivedIntangibleAssetsUsefulLife	7
CY2012	nwbi	Number Of Reportable Segments NumberOfReportableSegments	2	segment
CY2011Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	885408000	USD
CY2011Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	118237000	USD
CY2012Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	1053122000	USD
CY2012Q4	us-gaap	Availableforsale Securities Gross Unrealized Gain AvailableforsaleSecuritiesGrossUnrealizedGain	30279000	USD
CY2012Q4	us-gaap	Available For Sale Securities Gross Unrealized Losses1 AvailableForSaleSecuritiesGrossUnrealizedLosses1	4327000	USD
CY2012Q4	us-gaap	Available For Sale Securities Fair Value Disclosure AvailableForSaleSecuritiesFairValueDisclosure	1079074000	USD
CY2011Q4	us-gaap	Held To Maturity Securities Amortized Cost Before Other Than Temporary Impairment HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment	231389000	USD
CY2011Q4	us-gaap	Heldtomaturity Securities Unrecognized Holding Gain HeldtomaturitySecuritiesUnrecognizedHoldingGain	8023000	USD
CY2011Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	239412000	USD
CY2012Q4	us-gaap	Held To Maturity Securities Amortized Cost Before Other Than Temporary Impairment HeldToMaturitySecuritiesAmortizedCostBeforeOtherThanTemporaryImpairment	155081000	USD
CY2012Q4	us-gaap	Heldtomaturity Securities Unrecognized Holding Gain HeldtomaturitySecuritiesUnrecognizedHoldingGain	6902000	USD
CY2012Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	161969000	USD
CY2012Q4	us-gaap	Security Owned And Pledged As Collateral Fair Value SecurityOwnedAndPledgedAsCollateralFairValue	735500000	USD
CY2011Q4	us-gaap	Availableforsale Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses1 AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses1	638000	USD
CY2010	us-gaap	Available For Sale Securities Gross Realized Gains AvailableForSaleSecuritiesGrossRealizedGains	2300000	USD
CY2011Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	46374000	USD
CY2010	us-gaap	Available For Sale Securities Gross Realized Losses AvailableForSaleSecuritiesGrossRealizedLosses	147000	USD
CY2012	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	331000	USD
CY2011	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	937000	USD
CY2010	us-gaap	Other Than Temporary Impairment Losses Investments Portion Recognized In Earnings Net OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet	1500000	USD
CY2012Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	238873000	USD
CY2012Q4	us-gaap	Availableforsale Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses1 AvailableforsaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses1	1401000	USD
CY2012Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or Longer Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue	37237000	USD
CY2012Q4	us-gaap	Availableforsale Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses1 AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses1	2940000	USD
CY2012Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	276110000	USD
CY2012Q4	us-gaap	Availableforsale Securities Continuous Unrealized Loss Position Aggregate Losses1 AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses1	4341000	USD
CY2011Q4	us-gaap	Availableforsale Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses1 AvailableforsaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses1	5572000	USD
CY2011Q4	us-gaap	Available For Sale Securities Continuous Unrealized Loss Position Fair Value AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue	164611000	USD
CY2012	nwbi	Investment Description Of Variable Rate Basis InvestmentDescriptionOfVariableRateBasis	three-month LIBOR
CY2012	nwbi	Number Of Investment Positions With Unrealized Losses NumberOfInvestmentPositionsWithUnrealizedLosses	57	item
CY2012Q4	us-gaap	Cost Method Investments Aggregate Carrying Amount CostMethodInvestmentsAggregateCarryingAmount	1234000000	USD
CY2011Q4	us-gaap	Availableforsale Securities Continuous Unrealized Loss Position Aggregate Losses1 AvailableforsaleSecuritiesContinuousUnrealizedLossPositionAggregateLosses1	6210000	USD
CY2012Q4	nwbi	Amortized Cost Of Marketable Securities For Which Other Than Temporary Impairment Losses Recognized In Earnings AmortizedCostOfMarketableSecuritiesForWhichOtherThanTemporaryImpairmentLossesRecognizedInEarnings	20162000	USD
CY2012Q4	nwbi	Fair Value Of Marketable Securities For Which Other Than Temporary Impairment Losses Recognized In Earnings FairValueOfMarketableSecuritiesForWhichOtherThanTemporaryImpairmentLossesRecognizedInEarnings	20595000	USD
CY2012	us-gaap	Other Than Temporary Impairment Losses Investments Portion In Other Comprehensive Income Loss Before Tax Including Portion Attributable To Noncontrolling Interest OtherThanTemporaryImpairmentLossesInvestmentsPortionInOtherComprehensiveIncomeLossBeforeTaxIncludingPortionAttributableToNoncontrollingInterest	-433000	USD
CY2012Q4	nwbi	Other Than Temporary Impairment Losses Recognized In Earnings On Marketable Securities OtherThanTemporaryImpairmentLossesRecognizedInEarningsOnMarketableSecurities	17413000	USD
CY2011Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	11633000	USD
CY2012Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	9811000	USD
CY2010Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	15445000	USD
CY2011	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions Additional Credit Losses OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses	937000	USD
CY2012	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions Additional Credit Losses OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses	331000	USD
CY2012	us-gaap	Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Net Of Tax OtherComprehensiveIncomeReclassificationAdjustmentForSaleOfSecuritiesIncludedInNetIncomeNetOfTax	424000	USD
CY2012	us-gaap	Other Comprehensive Income Derivatives Qualifying As Hedges Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDerivativesQualifyingAsHedgesNetOfTaxPortionAttributableToParent	459000	USD
CY2012	us-gaap	Other Comprehensive Income Defined Benefit Plans Net Unamortized Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax	9576000	USD
CY2012	us-gaap	Other Comprehensive Income Amortization Of Defined Benefit Plan Net Prior Service Cost Recognized In Net Periodic Pension Cost Net Of Tax OtherComprehensiveIncomeAmortizationOfDefinedBenefitPlanNetPriorServiceCostRecognizedInNetPeriodicPensionCostNetOfTax	-104000	USD
CY2012	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	11738000	USD
CY2012	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	75298000	USD
CY2012	us-gaap	Stock Issued During Period Value Stock Options Exercised StockIssuedDuringPeriodValueStockOptionsExercised	2131000	USD
CY2012Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	73219000	USD
CY2011Q4	us-gaap	Qualitative And Quantitative Information Asset Or Liability Transferors Continuing Involvement Securitization Or Assetbacked Financing Principal Amount Outstanding Derecognized Amount QualitativeAndQuantitativeInformationAssetOrLiabilityTransferorsContinuingInvolvementSecuritizationOrAssetbackedFinancingPrincipalAmountOutstandingDerecognizedAmount	1150000000	USD
CY2010Q4	us-gaap	Qualitative And Quantitative Information Asset Or Liability Transferors Continuing Involvement Securitization Or Assetbacked Financing Principal Amount Outstanding Derecognized Amount QualitativeAndQuantitativeInformationAssetOrLiabilityTransferorsContinuingInvolvementSecuritizationOrAssetbackedFinancingPrincipalAmountOutstandingDerecognizedAmount	1310000000	USD
CY2012Q4	us-gaap	Qualitative And Quantitative Information Asset Or Liability Transferors Continuing Involvement Securitization Or Assetbacked Financing Principal Amount Outstanding Derecognized Amount QualitativeAndQuantitativeInformationAssetOrLiabilityTransferorsContinuingInvolvementSecuritizationOrAssetbackedFinancingPrincipalAmountOutstandingDerecognizedAmount	1036000000	USD
CY2011Q4	nwbi	Percentage Of Financing Receivable Portfolio Secured By Properties PercentageOfFinancingReceivablePortfolioSecuredByProperties	0.76	pure
CY2011Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	5635056000	USD
CY2011Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	4752000	USD
CY2011Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	71138000	USD
CY2012Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	5792509000	USD
CY2012Q4	us-gaap	Loans And Leases Receivable Deferred Income LoansAndLeasesReceivableDeferredIncome	1624000	USD
CY2012Q4	nwbi	Percentage Of Financing Receivable Portfolio Secured By Properties PercentageOfFinancingReceivablePortfolioSecuredByProperties	0.75	pure
CY2011Q4	us-gaap	Loans Receivable With Variable Rates Of Interest LoansReceivableWithVariableRatesOfInterest	1745000000	USD
CY2012Q4	us-gaap	Loans Receivable With Variable Rates Of Interest LoansReceivableWithVariableRatesOfInterest	1772000000	USD
CY2011Q4	us-gaap	Loans Receivable With Fixed Rates Of Interest LoansReceivableWithFixedRatesOfInterest	3890000000	USD
CY2012Q4	us-gaap	Loans Receivable With Fixed Rates Of Interest LoansReceivableWithFixedRatesOfInterest	4021000000	USD
CY2010Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	76412000	USD
CY2009Q4	us-gaap	Loans And Leases Receivable Allowance LoansAndLeasesReceivableAllowance	70403000	USD
CY2012	us-gaap	Allowance For Loan And Lease Losses Provision For Loss Net AllowanceForLoanAndLeaseLossesProvisionForLossNet	-30453000	USD
CY2011	us-gaap	Allowance For Loan And Lease Losses Provision For Loss Net AllowanceForLoanAndLeaseLossesProvisionForLossNet	-42364000	USD
CY2010	us-gaap	Allowance For Loan And Lease Losses Provision For Loss Net AllowanceForLoanAndLeaseLossesProvisionForLossNet	-36872000	USD
CY2012	us-gaap	Allowance For Loan And Lease Losses Recoveries Of Bad Debts AllowanceForLoanAndLeaseLossesRecoveriesOfBadDebts	-6196000	USD
CY2011	us-gaap	Allowance For Loan And Lease Losses Recoveries Of Bad Debts AllowanceForLoanAndLeaseLossesRecoveriesOfBadDebts	-2920000	USD
CY2010	us-gaap	Allowance For Loan And Lease Losses Recoveries Of Bad Debts AllowanceForLoanAndLeaseLossesRecoveriesOfBadDebts	-2395000	USD
CY2012Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	5702480000	USD
CY2011Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	5551519000	USD
CY2012Q4	nwbi	Loans And Leases Receivable Allowance Excluding Unallocated LoansAndLeasesReceivableAllowanceExcludingUnallocated	69193000	USD
CY2011Q4	nwbi	Loans And Leases Receivable Allowance Excluding Unallocated LoansAndLeasesReceivableAllowanceExcludingUnallocated	66722000	USD
CY2012Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	120212000	USD
CY2011Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	131105000	USD
CY2012Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	1698000	USD
CY2011Q4	us-gaap	Financing Receivable Recorded Investment90 Days Past Due And Still Accruing FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing	510000	USD
CY2012Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	89444000	USD
CY2011Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	69429000	USD
CY2011	nwbi	Financing Receivable Modification Pre Modification Recorded Investment FinancingReceivableModificationPreModificationRecordedInvestment	40184000	USD
CY2011	nwbi	Financing Receivable Modification Post Modification Recorded Investment FinancingReceivableModificationPostModificationRecordedInvestment	38204000	USD
CY2011	nwbi	Financing Receivable Modification Allowance For Credit Losses FinancingReceivableModificationAllowanceForCreditLosses	2132000	USD
CY2011Q4	us-gaap	Financing Receivable Recorded Investment Equal To Greater Than90 Days Past Due FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue	95836000	USD
CY2012Q4	us-gaap	Financing Receivable Recorded Investment Equal To Greater Than90 Days Past Due FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue	68347000	USD
CY2010Q4	us-gaap	Financing Receivable Recorded Investment Equal To Greater Than90 Days Past Due FinancingReceivableRecordedInvestmentEqualToGreaterThan90DaysPastDue	100421000	USD
CY2011Q4	nwbi	Financing Receivable Recorded Investment Less Than90 Days Past Due FinancingReceivableRecordedInvestmentLessThan90DaysPastDue	35269000	USD
CY2012Q4	nwbi	Financing Receivable Recorded Investment Less Than90 Days Past Due FinancingReceivableRecordedInvestmentLessThan90DaysPastDue	51865000	USD
CY2012	nwbi	Financing Receivable Modification Post Modification Recorded Investment FinancingReceivableModificationPostModificationRecordedInvestment	47244000	USD
CY2012	nwbi	Financing Receivable Modification Allowance For Credit Losses FinancingReceivableModificationAllowanceForCreditLosses	7010000	USD
CY2012	nwbi	Financing Receivable Modifications That Subsequently Defaulted Number Of Contracts FinancingReceivableModificationsThatSubsequentlyDefaultedNumberOfContracts	20	item
CY2012	nwbi	Financing Receivable Modification That Subsequently Defaulted Recorded Investment FinancingReceivableModificationThatSubsequentlyDefaultedRecordedInvestment	4855000	USD
CY2012	nwbi	Financing Receivable Modification That Subsequently Defaulted Pre Modification Recorded Investment FinancingReceivableModificationThatSubsequentlyDefaultedPreModificationRecordedInvestment	3440000	USD
CY2012	nwbi	Financing Receivable Modification That Subsequently Defaulted Allowance For Credit Losses FinancingReceivableModificationThatSubsequentlyDefaultedAllowanceForCreditLosses	1014000	USD
CY2011	nwbi	Financing Receivable Modification Number Of Contracts FinancingReceivableModificationNumberOfContracts	44	item
CY2011	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	204273000	USD
CY2010Q4	nwbi	Financing Receivable Recorded Investment Less Than90 Days Past Due FinancingReceivableRecordedInvestmentLessThan90DaysPastDue	47970000	USD
CY2011Q4	nwbi	Financing Receivable Recorded Accruing Loans Reviewed For Impairment FinancingReceivableRecordedAccruingLoansReviewedForImpairment	22804000	USD
CY2012Q4	nwbi	Financing Receivable Recorded Accruing Loans Reviewed For Impairment FinancingReceivableRecordedAccruingLoansReviewedForImpairment	33282000	USD
CY2012	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	190476000	USD
CY2010Q4	nwbi	Financing Receivable Recorded Accruing Loans Reviewed For Impairment FinancingReceivableRecordedAccruingLoansReviewedForImpairment	42483000	USD
CY2011Q4	nwbi	Financing Receivable Recorded Accruing Loans Not Reviewed For Impairment FinancingReceivableRecordedAccruingLoansNotReviewedForImpairment	25449000	USD
CY2012Q4	nwbi	Financing Receivable Recorded Accruing Loans Not Reviewed For Impairment FinancingReceivableRecordedAccruingLoansNotReviewedForImpairment	30817000	USD
CY2010Q4	nwbi	Financing Receivable Recorded Accruing Loans Not Reviewed For Impairment FinancingReceivableRecordedAccruingLoansNotReviewedForImpairment	6222000	USD
CY2011Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	179358000	USD
CY2012Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	184311000	USD
CY2010Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	197096000	USD
CY2010	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	183703000	USD
CY2011	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	6036000	USD
CY2012	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	6524000	USD
CY2010	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	5151000	USD
CY2011Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	5437616000	USD
CY2012Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	5577095000	USD
CY2011Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	113903000	USD
CY2012Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	125385000	USD
CY2011Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	11145000	USD
CY2012Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	16607000	USD
CY2012	nwbi	Financing Receivable Modification Number Of Contracts FinancingReceivableModificationNumberOfContracts	201	item
CY2012	nwbi	Financing Receivable Modification Pre Modification Recorded Investment FinancingReceivableModificationPreModificationRecordedInvestment	56845000	USD
CY2011	nwbi	Financing Receivable Modifications That Subsequently Defaulted Number Of Contracts FinancingReceivableModificationsThatSubsequentlyDefaultedNumberOfContracts	12	item
CY2011	nwbi	Financing Receivable Modification That Subsequently Defaulted Recorded Investment FinancingReceivableModificationThatSubsequentlyDefaultedRecordedInvestment	14480000	USD
CY2011	nwbi	Financing Receivable Modification That Subsequently Defaulted Pre Modification Recorded Investment FinancingReceivableModificationThatSubsequentlyDefaultedPreModificationRecordedInvestment	3603000	USD
CY2011	nwbi	Financing Receivable Modification That Subsequently Defaulted Allowance For Credit Losses FinancingReceivableModificationThatSubsequentlyDefaultedAllowanceForCreditLosses	793000	USD
CY2010	nwbi	Financing Receivable Modification Number Of Contracts FinancingReceivableModificationNumberOfContracts	27	item
CY2010	nwbi	Financing Receivable Modification Pre Modification Recorded Investment FinancingReceivableModificationPreModificationRecordedInvestment	32020000	USD
CY2010	nwbi	Financing Receivable Modification Post Modification Recorded Investment FinancingReceivableModificationPostModificationRecordedInvestment	31614000	USD
CY2010	nwbi	Financing Receivable Modification Allowance For Credit Losses FinancingReceivableModificationAllowanceForCreditLosses	4196000	USD
CY2010	nwbi	Financing Receivable Modifications That Subsequently Defaulted Number Of Contracts FinancingReceivableModificationsThatSubsequentlyDefaultedNumberOfContracts	3	item
CY2010	nwbi	Financing Receivable Modification That Subsequently Defaulted Recorded Investment FinancingReceivableModificationThatSubsequentlyDefaultedRecordedInvestment	11470000	USD
CY2010	nwbi	Financing Receivable Modification That Subsequently Defaulted Pre Modification Recorded Investment FinancingReceivableModificationThatSubsequentlyDefaultedPreModificationRecordedInvestment	11668000	USD
CY2010	nwbi	Financing Receivable Modification That Subsequently Defaulted Allowance For Credit Losses FinancingReceivableModificationThatSubsequentlyDefaultedAllowanceForCreditLosses	114000	USD
CY2012Q4	us-gaap	Financing Receivable Recorded Investment30 To59 Days Past Due FinancingReceivableRecordedInvestment30To59DaysPastDue	61145000	USD
CY2011Q4	us-gaap	Financing Receivable Recorded Investment30 To59 Days Past Due FinancingReceivableRecordedInvestment30To59DaysPastDue	58658000	USD
CY2012Q4	us-gaap	Financing Receivable Recorded Investment60 To89 Days Past Due FinancingReceivableRecordedInvestment60To89DaysPastDue	27948000	USD
CY2011Q4	us-gaap	Financing Receivable Recorded Investment60 To89 Days Past Due FinancingReceivableRecordedInvestment60To89DaysPastDue	20449000	USD
CY2012Q4	us-gaap	Financing Receivable Recorded Investment Past Due FinancingReceivableRecordedInvestmentPastDue	157440000	USD
CY2011Q4	us-gaap	Financing Receivable Recorded Investment Past Due FinancingReceivableRecordedInvestmentPastDue	174943000	USD
CY2012Q4	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	5545040000	USD
CY2012Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	136382000	USD
CY2011Q4	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	5376576000	USD
CY2011Q4	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Liability FairValueDisclosureOffbalanceSheetRisksAmountLiability	598574000	USD
CY2012Q4	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Liability FairValueDisclosureOffbalanceSheetRisksAmountLiability	525780000	USD
CY2011Q4	nwbi	Accrued Interest Receivable On Investments AccruedInterestReceivableOnInvestments	2402000	USD
CY2011Q4	nwbi	Accrued Interest Receivable On Mortgage Backed Securities AccruedInterestReceivableOnMortgageBackedSecurities	1777000	USD
CY2011Q4	nwbi	Accrued Interest Receivable On Loans AccruedInterestReceivableOnLoans	20420000	USD
CY2012Q4	nwbi	Accrued Interest Receivable On Investments AccruedInterestReceivableOnInvestments	2354000	USD
CY2012Q4	nwbi	Accrued Interest Receivable On Mortgage Backed Securities AccruedInterestReceivableOnMortgageBackedSecurities	1359000	USD
CY2012Q4	nwbi	Accrued Interest Receivable On Loans AccruedInterestReceivableOnLoans	19600000	USD
CY2012	nwbi	Minimum Investment In Federal Home Loan Bank Stock As Percentage Of Borrowings Outstanding MinimumInvestmentInFederalHomeLoanBankStockAsPercentageOfBorrowingsOutstanding	0.0460	pure
CY2012	nwbi	Minimum Investment In Federal Home Loan Bank Stock As Pecentage Of Asset Value Defined By Fhlb MinimumInvestmentInFederalHomeLoanBankStockAsPecentageOfAssetValueDefinedByFHLB	0.0035	pure
CY2012	nwbi	Minimum Investment In Federal Home Loan Bank Stock As Percentage Of Certain Letters Of Credit MinimumInvestmentInFederalHomeLoanBankStockAsPercentageOfCertainLettersOfCredit	0.0160	pure
CY2011	nwbi	Excess Stock Repurchased By Fhlb ExcessStockRepurchasedByFHLB	11100000	USD
CY2012	nwbi	Excess Stock Repurchased By Fhlb ExcessStockRepurchasedByFHLB	2100000	USD
CY2011Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	263742000	USD
CY2012Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	275206000	USD
CY2011Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	131590000	USD
CY2011	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	11700000	USD
CY2010	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	12600000	USD
CY2012	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	11500000	USD
CY2012Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	3883000	USD
CY2012Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	3220000	USD
CY2012Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	2669000	USD
CY2012Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	2180000	USD
CY2012Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	1742000	USD
CY2012Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	7007000	USD
CY2012Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	20701000	USD
CY2011	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	4300000	USD
CY2010	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	4900000	USD
CY2012	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	4900000	USD
CY2012	us-gaap	Future Amortization Expense Year One FutureAmortizationExpenseYearOne	1210000	USD
CY2012	us-gaap	Future Amortization Expense Year Two FutureAmortizationExpenseYearTwo	814000	USD
CY2012	us-gaap	Future Amortization Expense Year Three FutureAmortizationExpenseYearThree	571000	USD
CY2012	us-gaap	Future Amortization Expense Year Four FutureAmortizationExpenseYearFour	415000	USD
CY2012	us-gaap	Future Amortization Expense Year Five FutureAmortizationExpenseYearFive	259000	USD
CY2010Q4	us-gaap	Goodwill Goodwill	171882000	USD
CY2010Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.12
CY2011Q4	us-gaap	Noninterest Bearing Domestic Deposit Checking NoninterestBearingDomesticDepositChecking	658560000	USD
CY2011Q4	us-gaap	Deposits Money Market Deposits DepositsMoneyMarketDeposits	963994000	USD
CY2011Q4	us-gaap	Time Deposits TimeDeposits	2284817000	USD
CY2012Q4	us-gaap	Time Deposits100000 Or More TimeDeposits100000OrMore	475500000	USD
CY2012Q4	us-gaap	Time Deposits TimeDeposits	1886089000	USD
CY2011Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	132191000	USD
CY2011Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	122766000	USD
CY2011Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	1072278000	USD
CY2011Q4	us-gaap	Interest Bearing Domestic Deposit Checking InterestBearingDomesticDepositChecking	800676000	USD
CY2011Q4	us-gaap	Time Deposits100000 Or More TimeDeposits100000OrMore	596300000	USD
CY2012Q4	us-gaap	Deposits Savings Deposits DepositsSavingsDeposits	1158795000	USD
CY2012Q4	us-gaap	Interest Bearing Domestic Deposit Checking InterestBearingDomesticDepositChecking	851771000	USD
CY2012Q4	us-gaap	Noninterest Bearing Domestic Deposit Checking NoninterestBearingDomesticDepositChecking	755429000	USD
CY2012Q4	us-gaap	Deposits Money Market Deposits DepositsMoneyMarketDeposits	1112516000	USD
CY2012Q4	nwbi	Maximum Amount Of Deposits That Are Federally Insured MaximumAmountOfDepositsThatAreFederallyInsured	250000	USD
CY2012	nwbi	Number Of Customers Participating In Certificate Of Deposit Account Registry Service Program NumberOfCustomersParticipatingInCertificateOfDepositAccountRegistryServiceProgram	6	customer
CY2012Q4	nwbi	Deposits Under Certificate Of Deposit Account Registry Service Program DepositsUnderCertificateOfDepositAccountRegistryServiceProgram	733000	USD
CY2012Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	871580000	USD
CY2012Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	232392000	USD
CY2012Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	206578000	USD
CY2012Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	275723000	USD
CY2012Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	281683000	USD
CY2012Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	18133000	USD
CY2011Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	1356963000	USD
CY2011Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	356456000	USD
CY2011Q4	us-gaap	Time Deposit Maturities Year Five TimeDepositMaturitiesYearFive	252181000	USD
CY2011Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	64260000	USD
CY2012	us-gaap	Interest Expense Savings Deposits InterestExpenseSavingsDeposits	4219000	USD
CY2012	us-gaap	Interest Expense Domestic Deposit Liabilities Checking InterestExpenseDomesticDepositLiabilitiesChecking	792000	USD
CY2012	us-gaap	Interest Expense Money Market Deposits InterestExpenseMoneyMarketDeposits	3605000	USD
CY2012	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	34761000	USD
CY2011	us-gaap	Interest Expense Savings Deposits InterestExpenseSavingsDeposits	5000000	USD
CY2011	us-gaap	Interest Expense Domestic Deposit Liabilities Checking InterestExpenseDomesticDepositLiabilitiesChecking	960000	USD
CY2011	us-gaap	Interest Expense Money Market Deposits InterestExpenseMoneyMarketDeposits	4243000	USD
CY2011	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	50518000	USD
CY2010	us-gaap	Interest Expense Savings Deposits InterestExpenseSavingsDeposits	8166000	USD
CY2010	us-gaap	Interest Expense Domestic Deposit Liabilities Checking InterestExpenseDomesticDepositLiabilitiesChecking	1211000	USD
CY2010	us-gaap	Interest Expense Money Market Deposits InterestExpenseMoneyMarketDeposits	5977000	USD
CY2010	us-gaap	Interest Expense Time Deposits InterestExpenseTimeDeposits	59820000	USD
CY2012	nwbi	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Available For Sale Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesAvailableForSaleArisingDuringPeriodTax	1204000	USD
CY2011	nwbi	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Available For Sale Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesAvailableForSaleArisingDuringPeriodTax	7029000	USD
CY2010	nwbi	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Available For Sale Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesAvailableForSaleArisingDuringPeriodTax	-1173000	USD
CY2012	nwbi	Other Comprehensive Income Tax Benefit From Excess Of Fair Value Over Cost Of Stock Benefit Plans OtherComprehensiveIncomeTaxBenefitFromExcessOfFairValueOverCostOfStockBenefitPlans	403000	USD
CY2011	nwbi	Other Comprehensive Income Tax Benefit From Excess Of Fair Value Over Cost Of Stock Benefit Plans OtherComprehensiveIncomeTaxBenefitFromExcessOfFairValueOverCostOfStockBenefitPlans	610000	USD
CY2010	nwbi	Other Comprehensive Income Tax Benefit From Excess Of Fair Value Over Cost Of Stock Benefit Plans OtherComprehensiveIncomeTaxBenefitFromExcessOfFairValueOverCostOfStockBenefitPlans	369000	USD
CY2012	us-gaap	Other Comprehensive Income Defined Benefit Plans Tax OtherComprehensiveIncomeDefinedBenefitPlansTax	6056000	USD
CY2011	us-gaap	Other Comprehensive Income Defined Benefit Plans Tax OtherComprehensiveIncomeDefinedBenefitPlansTax	-11487000	USD
CY2010	us-gaap	Other Comprehensive Income Defined Benefit Plans Tax OtherComprehensiveIncomeDefinedBenefitPlansTax	758000	USD
CY2012	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	246000	USD
CY2011	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	-1506000	USD
CY2010	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	-1534000	USD
CY2012	nwbi	Income Tax Expense Benefit Unallocated IncomeTaxExpenseBenefitUnallocated	34334000	USD
CY2011	nwbi	Income Tax Expense Benefit Unallocated IncomeTaxExpenseBenefitUnallocated	20283000	USD
CY2010	nwbi	Income Tax Expense Benefit Unallocated IncomeTaxExpenseBenefitUnallocated	21204000	USD
CY2012	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	23073000	USD
CY2011	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	19108000	USD
CY2010	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	23091000	USD
CY2012	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350	pure
CY2011	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350	pure
CY2010	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.350	pure
CY2012	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.050	pure
CY2011	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.054	pure
CY2010	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.059	pure
CY2012	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.028	pure
CY2011	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.029	pure
CY2010	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.027	pure
CY2012	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Life Insurance EffectiveIncomeTaxRateReconciliationNondeductibleExpenseLifeInsurance	-0.019	pure
CY2011	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Life Insurance EffectiveIncomeTaxRateReconciliationNondeductibleExpenseLifeInsurance	-0.023	pure
CY2010	us-gaap	Effective Income Tax Rate Reconciliation Nondeductible Expense Life Insurance EffectiveIncomeTaxRateReconciliationNondeductibleExpenseLifeInsurance	-0.022	pure
CY2012	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.003	pure
CY2011	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.002	pure
CY2010	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.003	pure
CY2012	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.293	pure
CY2011	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.295	pure
CY2010	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.290	pure
CY2012Q4	us-gaap	Deferred Tax Assets Deferred Income DeferredTaxAssetsDeferredIncome	280000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Deferred Income DeferredTaxAssetsDeferredIncome	363000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	2845000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	758000	USD
CY2010	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	108309000	shares
CY2012	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	288000	shares
CY2011	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	376000	shares
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	21464000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	736000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	911000	USD
CY2011Q4	nwbi	Deferred Tax Asset From Investment Securities Write Down DeferredTaxAssetFromInvestmentSecuritiesWriteDown	6700000	USD
CY2011Q4	nwbi	Deferred Tax Asset Expense Resulting From Increase Decrease In Uncollected Interest Reserve DeferredTaxAssetExpenseResultingFromIncreaseDecreaseInUncollectedInterestReserve	6194000	USD
CY2011Q4	nwbi	Deferred Tax Assets Expense Compensation And Pension Benefits And Other Postretirement Benefits DeferredTaxAssetsExpenseCompensationAndPensionBenefitsAndOtherPostretirementBenefits	18162000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	4773000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	364000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	63375000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Employee Compensation DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation	3463000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	482000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts	20639000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	734000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	1128000	USD
CY2012Q4	nwbi	Deferred Tax Asset From Investment Securities Write Down DeferredTaxAssetFromInvestmentSecuritiesWriteDown	6032000	USD
CY2012Q4	nwbi	Deferred Tax Asset Expense Resulting From Increase Decrease In Uncollected Interest Reserve DeferredTaxAssetExpenseResultingFromIncreaseDecreaseInUncollectedInterestReserve	4194000	USD
CY2012Q4	nwbi	Deferred Tax Assets Expense Compensation And Pension Benefits And Other Postretirement Benefits DeferredTaxAssetsExpenseCompensationAndPensionBenefitsAndOtherPostretirementBenefits	12106000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Derivative Instruments DeferredTaxAssetsDerivativeInstruments	4527000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	582000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	55057000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Prepaid Pension Costs DeferredTaxLiabilitiesPrepaidPensionCosts	6704000	USD
CY2011Q4	nwbi	Deferred Tax Liabilities Available For Sale Securities DeferredTaxLiabilitiesAvailableForSaleSecurities	8894000	USD
CY2011Q4	nwbi	Deferred Tax Liabilities Purchase Accounting DeferredTaxLiabilitiesPurchaseAccounting	1030000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	16202000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Mortgage Servicing Rights DeferredTaxLiabilitiesMortgageServicingRights	1279000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	7064000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	737000	USD
CY2011Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	41910000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	21465000	USD
CY2012Q4	us-gaap	Deferred Tax Liabilities Prepaid Pension Costs DeferredTaxLiabilitiesPrepaidPensionCosts	5606000	USD
CY2012Q4	nwbi	Deferred Tax Liabilities Available For Sale Securities DeferredTaxLiabilitiesAvailableForSaleSecurities	10098000	USD
CY2012Q4	nwbi	Deferred Tax Liabilities Purchase Accounting DeferredTaxLiabilitiesPurchaseAccounting	1808000	USD
CY2012Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	17958000	USD
CY2012Q4	us-gaap	Deferred Tax Liabilities Mortgage Servicing Rights DeferredTaxLiabilitiesMortgageServicingRights	1151000	USD
CY2012Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	7814000	USD
CY2012Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	821000	USD
CY2012Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	45256000	USD
CY2012Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	9801000	USD
CY2012Q4	nwbi	Bad Debt Deduction For Which No Deferred Taxes Have Been Provided BadDebtDeductionForWhichNoDeferredTaxesHaveBeenProvided	39100000	USD
CY2011Q4	nwbi	Bad Debt Deduction For Which No Deferred Taxes Have Been Provided BadDebtDeductionForWhichNoDeferredTaxesHaveBeenProvided	39100000	USD
CY2012	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	93913000	shares
CY2011	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	99802000	shares
CY2010	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	622000	shares
CY2012	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	94201000	shares
CY2011	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	100178000	shares
CY2010	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	108931000	shares
CY2012Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	6915000	USD
CY2012Q4	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8173000	USD
CY2012Q4	us-gaap	Assets Fair Value Disclosure Nonrecurring AssetsFairValueDisclosureNonrecurring	110658000	USD
CY2011Q4	us-gaap	Assets Fair Value Disclosure Nonrecurring AssetsFairValueDisclosureNonrecurring	80983000	USD
CY2012Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	15853000	USD
CY2012Q1	us-gaap	Noninterest Income NoninterestIncome	13640000	USD
CY2011Q4	us-gaap	Accumulated Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	14046000	USD
CY2012Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-8405000	USD
CY2011Q4	us-gaap	Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Net Of Tax AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax	-8864000	USD
CY2012Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	18936000	USD
CY2011Q4	us-gaap	Accumulated Other Comprehensive Income Loss Defined Benefit Pension And Other Postretirement Plans Net Of Tax AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax	28408000	USD
CY2012	nwbi	Number Of Reportable Business Segments NumberOfReportableBusinessSegments	2	segment
CY2010Q4	us-gaap	Assets Assets	8148155000	USD
CY2012Q4	nwbi	Number Of Business Trusts Owned NumberOfBusinessTrustsOwned	2	item
CY2012Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	86249000	USD
CY2012Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	85057000	USD
CY2012Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	84214000	USD
CY2012Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	83655000	USD
CY2012Q1	us-gaap	Interest Expense InterestExpense	20843000	USD
CY2012Q2	us-gaap	Interest Expense InterestExpense	19096000	USD
CY2012Q3	us-gaap	Interest Expense InterestExpense	18220000	USD
CY2012Q4	us-gaap	Interest Expense InterestExpense	17040000	USD
CY2012Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	65406000	USD
CY2012Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	65961000	USD
CY2012Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	65994000	USD
CY2012Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	66615000	USD
CY2012Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	6287000	USD
CY2012Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	4963000	USD
CY2012Q2	us-gaap	Noninterest Income NoninterestIncome	14837000	USD
CY2011Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8057000	USD
CY2011Q4	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	10502000	USD
CY2011Q1	us-gaap	Noninterest Income NoninterestIncome	14326000	USD
CY2011Q2	us-gaap	Noninterest Income NoninterestIncome	15262000	USD
CY2011Q4	us-gaap	Interest Expense InterestExpense	22268000	USD
CY2011Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	67040000	USD
CY2011Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	66679000	USD
CY2011Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	67012000	USD
CY2011Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	66538000	USD
CY2011Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	7244000	USD
CY2011Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8367000	USD
CY2012Q3	us-gaap	Noninterest Income NoninterestIncome	14935000	USD
CY2012Q4	us-gaap	Noninterest Income NoninterestIncome	14355000	USD
CY2012Q1	us-gaap	Noninterest Expense NoninterestExpense	51276000	USD
CY2012Q2	us-gaap	Noninterest Expense NoninterestExpense	51966000	USD
CY2012Q3	us-gaap	Noninterest Expense NoninterestExpense	51803000	USD
CY2012Q4	us-gaap	Noninterest Expense NoninterestExpense	50432000	USD
CY2012Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	21483000	USD
CY2012Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	23869000	USD
CY2012Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	22211000	USD
CY2012Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	22365000	USD
CY2012Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	6302000	USD
CY2012Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	7508000	USD
CY2012Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	6518000	USD
CY2012Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	6040000	USD
CY2012Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	15181000	USD
CY2012Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	16361000	USD
CY2012Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	15693000	USD
CY2012Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	16325000	USD
CY2012Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.16
CY2012Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.17
CY2012Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.17
CY2012Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.18
CY2012Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.16
CY2012Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.17
CY2012Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.17
CY2012Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.18
CY2011Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	91092000	USD
CY2011Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	90141000	USD
CY2011Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	90031000	USD
CY2011Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	88806000	USD
CY2011Q1	us-gaap	Interest Expense InterestExpense	24052000	USD
CY2011Q2	us-gaap	Interest Expense InterestExpense	23462000	USD
CY2011Q3	us-gaap	Interest Expense InterestExpense	23019000	USD
CY2011Q3	us-gaap	Noninterest Income NoninterestIncome	14510000	USD
CY2011Q4	us-gaap	Noninterest Income NoninterestIncome	14038000	USD
CY2011Q1	us-gaap	Noninterest Expense NoninterestExpense	49378000	USD
CY2011Q2	us-gaap	Noninterest Expense NoninterestExpense	52490000	USD
CY2011Q3	us-gaap	Noninterest Expense NoninterestExpense	49923000	USD
CY2011Q4	us-gaap	Noninterest Expense NoninterestExpense	48436000	USD
CY2011Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	24744000	USD
CY2011Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	21084000	USD
CY2011Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	23542000	USD
CY2011Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	21638000	USD
CY2011Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	7491000	USD
CY2011Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	6081000	USD
CY2011Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	6822000	USD
CY2011Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	6463000	USD
CY2011Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	17253000	USD
CY2011Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	15003000	USD
CY2011Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	16720000	USD
CY2011Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	15175000	USD
CY2011Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.16
CY2011Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.15
CY2011Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.17
CY2011Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.16
CY2011Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.16
CY2011Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.15
CY2011Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.17
CY2011Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.16
CY2010Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	91138000	USD
CY2010Q2	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	92404000	USD
CY2010Q3	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	94009000	USD
CY2010Q4	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	93017000	USD
CY2010Q1	us-gaap	Interest Expense InterestExpense	31104000	USD
CY2010Q2	us-gaap	Interest Expense InterestExpense	28677000	USD
CY2010Q3	us-gaap	Interest Expense InterestExpense	27359000	USD
CY2010Q4	us-gaap	Interest Expense InterestExpense	25787000	USD
CY2010Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	60034000	USD
CY2010Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	63727000	USD
CY2010Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	66650000	USD
CY2010Q4	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	67230000	USD
CY2010Q1	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8801000	USD
CY2010Q2	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	7896000	USD
CY2010Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	9871000	USD
CY2010Q4	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	13918000	USD
CY2010Q1	us-gaap	Noninterest Income NoninterestIncome	15857000	USD
CY2010Q2	us-gaap	Noninterest Income NoninterestIncome	15545000	USD
CY2010Q3	us-gaap	Noninterest Income NoninterestIncome	13828000	USD
CY2010Q4	us-gaap	Noninterest Income NoninterestIncome	15168000	USD
CY2010Q1	us-gaap	Noninterest Expense NoninterestExpense	48604000	USD
CY2010Q2	us-gaap	Noninterest Expense NoninterestExpense	48157000	USD
CY2010Q3	us-gaap	Noninterest Expense NoninterestExpense	49048000	USD
CY2010Q4	us-gaap	Noninterest Expense NoninterestExpense	50699000	USD
CY2010Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	18486000	USD
CY2010Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	23219000	USD
CY2010Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	21559000	USD
CY2010Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	17781000	USD
CY2010Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	5333000	USD
CY2010Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	7078000	USD
CY2010Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	6068000	USD
CY2010Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	5043000	USD
CY2010Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	13153000	USD
CY2010Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	16141000	USD
CY2010Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	15491000	USD
CY2010Q4	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	12738000	USD
CY2010Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.15
CY2010Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.14
CY2010Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.12
CY2010Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.12
CY2010Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.15
CY2010Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.14
CY2010Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.12
CY2012Q4	us-gaap	Held To Maturity Securities Unrecognized Holding Loss HeldToMaturitySecuritiesUnrecognizedHoldingLoss	14000	USD
CY2012Q2	dei	Entity Public Float EntityPublicFloat	1146000000	USD
CY2013Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	93681947	shares
CY2012	us-gaap	Effective Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends EffectiveIncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	0.013	pure
CY2011	us-gaap	Effective Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends EffectiveIncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	0.009	pure
CY2010	us-gaap	Effective Income Tax Rate Reconciliation Deductions Employee Stock Ownership Plan Dividends EffectiveIncomeTaxRateReconciliationDeductionsEmployeeStockOwnershipPlanDividends	0.009	pure
CY2012Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	890000	USD
CY2011Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	105000	USD
CY2012	us-gaap	Goodwill Acquired During Period GoodwillAcquiredDuringPeriod	2579000	USD
CY2012	nwbi	Federal Home Loan Bank Stock Dividend Received FederalHomeLoanBankStockDividendReceived	87000	USD
CY2011	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Securities Sold OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsSecuritiesSold	4749000	USD
CY2012	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Securities Sold OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsSecuritiesSold	2153000	USD
CY2012Q4	us-gaap	Intangible Assets Net Excluding Goodwill IntangibleAssetsNetExcludingGoodwill	3529000	USD
CY2012	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	23000	USD
CY2012	nwbi	Financing Receivable Ninety Days Past Due And Still Accruing FinancingReceivableNinetyDaysPastDueAndStillAccruing	90
CY2012Q4	nwbi	Deposits250000 Or More Deposits250000OrMore	1024000000	USD
CY2012Q4	us-gaap	Loss Contingency Accrual At Carrying Value LossContingencyAccrualAtCarryingValue	2200000	USD

Files In Submission

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$NWBI
Northwest Bancshares, Inc. Stock $nwbi

2011 Q4 Form 10-K Financial Statement

#000110465913016545 Filed on March 01, 2013

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NWBI Northwest Bancshares, Inc. Stock $nwbi

2011 Q4 Form 10-K Financial Statement

#000110465913016545 Filed on March 01, 2013

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NWBI
Northwest Bancshares, Inc. Stock $nwbi