$SLG
SL Green Realty Corp Stock $slg

$slg Overview Financials Valuation SEC Filings Company Website

2021 Q1 Form 10-Q Financial Statement

#000104097121000017 Filed on May 10, 2021

Income Statement

Concept	2021 Q1	2020 Q1
Revenue	$226.1M	$314.3M
YoY Change	-28.06%	3.3%
Cost Of Revenue	$94.40M	$107.9M
YoY Change	-12.51%	-4.26%
Gross Profit	$131.7M	$206.4M
YoY Change	-36.19%	7.72%
Gross Profit Margin	58.25%	65.67%
Selling, General & Admin	$22.90M	$19.60M
YoY Change	16.84%	-24.62%
% of Gross Profit	17.39%	9.5%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$66.77M	$70.78M
YoY Change	-5.66%	-0.43%
% of Gross Profit	50.7%	34.29%
Operating Expenses	$22.90M	$19.60M
YoY Change	16.84%	-24.62%
Operating Profit	$108.8M	$186.8M
YoY Change	-41.76%	12.8%
Interest Expense	$39.87M	$56.81M
YoY Change	-29.83%	-6.57%
% of Operating Profit	36.64%	30.41%
Other Income/Expense, Net	-$8.200M
YoY Change
Pretax Income	-$3.900M	$127.1M
YoY Change	-103.07%	140.72%
Income Tax	$700.0K	$1.100M
% Of Pretax Income		0.87%
Net Earnings	-$3.726M	$118.5M
YoY Change	-103.14%	149.4%
Net Earnings / Revenue	-1.65%	37.71%
Basic Earnings Per Share	-$0.12	$1.51
Diluted Earnings Per Share	-$0.12	$1.51
COMMON SHARES
Basic Shares Outstanding	66.96M shares	75.66M shares
Diluted Shares Outstanding	72.00M shares	80.35M shares

Balance Sheet

Concept	2021 Q1	2020 Q1
SHORT-TERM ASSETS
Cash & Short-Term Investments	$328.8M	$579.5M
YoY Change	-43.27%	233.59%
Cash & Equivalents	$305.0M	$554.2M
Short-Term Investments	$23.78M	$25.35M
Other Short-Term Assets
YoY Change
Inventory		$0.00
Prepaid Expenses
Receivables	$381.0M	$425.0M
Other Receivables	$0.00	$0.00
Total Short-Term Assets	$686.0M	$979.0M
YoY Change	-29.93%	75.45%
LONG-TERM ASSETS
Property, Plant & Equipment	$5.826B	$6.932B
YoY Change	-15.95%	2.21%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments	$3.699B	$2.848B
YoY Change	29.85%	-6.78%
Other Assets	$267.0M	$299.0M
YoY Change	-10.7%	-17.63%
Total Long-Term Assets	$11.36B	$12.24B
YoY Change	-7.22%	-4.57%
TOTAL ASSETS
Total Short-Term Assets	$686.0M	$979.0M
Total Long-Term Assets	$11.36B	$12.24B
Total Assets	$12.04B	$13.22B
YoY Change	-8.9%	-1.23%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$120.0M	$159.0M
YoY Change	-24.53%	41.96%
Accrued Expenses	$478.0M	$390.0M
YoY Change	22.56%	-6.92%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$677.0M	$635.0M
YoY Change	6.61%	-5.51%
LONG-TERM LIABILITIES
Long-Term Debt	$5.471B	$6.286B
YoY Change	-12.97%	5.93%
Other Long-Term Liabilities	$387.0M	$331.0M
YoY Change	16.92%	39.08%
Total Long-Term Liabilities	$5.858B	$6.617B
YoY Change	-11.47%	7.21%
TOTAL LIABILITIES
Total Short-Term Liabilities	$677.0M	$635.0M
Total Long-Term Liabilities	$5.858B	$6.617B
Total Liabilities	$6.536B	$7.252B
YoY Change	-9.87%	5.96%
SHAREHOLDERS EQUITY
Retained Earnings	$918.1M	$1.099B
YoY Change	-16.49%	-9.18%
Common Stock	$705.0K	$776.0K
YoY Change	-9.15%	-7.95%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$124.0M	$124.0M
YoY Change	0.0%	0.0%
Treasury Stock Shares	1.026M shares	1.055M shares
Shareholders Equity	$4.911B	$5.263B
YoY Change
Total Liabilities & Shareholders Equity	$12.04B	$13.22B
YoY Change	-8.9%	-1.23%

Cashflow Statement

Concept	2021 Q1	2020 Q1
OPERATING ACTIVITIES
Net Income	-$3.726M	$118.5M
YoY Change	-103.14%	149.4%
Depreciation, Depletion And Amortization	$66.77M	$70.78M
YoY Change	-5.66%	-0.43%
Cash From Operating Activities	$18.60M	$42.03M
YoY Change	-55.74%	-32.56%
INVESTING ACTIVITIES
Capital Expenditures	-$49.30M	-$188.6M
YoY Change	-73.86%	377.47%
Acquisitions
YoY Change
Other Investing Activities	$69.50M	$59.20M
YoY Change	17.4%	-123.46%
Cash From Investing Activities	$20.18M	-$129.4M
YoY Change	-115.59%	-55.65%
FINANCING ACTIVITIES
Cash Dividend Paid	$69.77M	$79.66M
YoY Change	-12.41%	2.92%
Common Stock Issuance & Retirement, Net	$84.09M	$219.6M
YoY Change	-61.7%	541.23%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-$9.971M	$467.0M
YoY Change	-102.14%	89.73%
NET CHANGE
Cash From Operating Activities	$18.60M	$42.03M
Cash From Investing Activities	$20.18M	-$129.4M
Cash From Financing Activities	-$9.971M	$467.0M
Net Change In Cash	$28.81M	$379.6M
YoY Change	-92.41%	2186.97%
FREE CASH FLOW
Cash From Operating Activities	$18.60M	$42.03M
Capital Expenditures	-$49.30M	-$188.6M
Free Cash Flow	$67.90M	$230.6M
YoY Change	-70.56%	126.52%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2021Q1	dei	Entity Central Index Key EntityCentralIndexKey	0001040971
CY2021Q1	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2021Q1	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
CY2019	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201613Member
CY2021Q1	dei	Document Type DocumentType	10-Q
CY2021Q1	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q1
CY2021Q1	dei	Amendment Flag AmendmentFlag	false
CY2020Q1	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201613Member
CY2021Q1	dei	Document Quarterly Report DocumentQuarterlyReport	true
CY2021Q1	dei	Document Period End Date DocumentPeriodEndDate	2021-03-31
CY2021Q1	dei	Document Transition Report DocumentTransitionReport	false
CY2021Q1	dei	Entity File Number EntityFileNumber	1-13199
CY2021Q1	dei	Entity Registrant Name EntityRegistrantName	SL GREEN REALTY CORP
CY2021Q1	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MD
CY2021Q1	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	13-3956775
CY2021Q1	dei	Entity Address Address Line1 EntityAddressAddressLine1	One Vanderbilt Avenue
CY2021Q1	dei	Entity Address City Or Town EntityAddressCityOrTown	New York
CY2021Q1	dei	Entity Address State Or Province EntityAddressStateOrProvince	NY
CY2021Q1	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	10017
CY2021Q1	dei	City Area Code CityAreaCode	212
CY2021Q1	dei	Local Phone Number LocalPhoneNumber	594-2700
CY2021Q1	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2021Q1	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2021Q1	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2021Q1	dei	Entity Small Business EntitySmallBusiness	false
CY2021Q1	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2021Q1	dei	Entity Shell Company EntityShellCompany	false
CY2021Q2	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	69353968	shares
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CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	-3726000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	118539000	USD
CY2021Q1	us-gaap	Dividends Preferred Stock DividendsPreferredStock	3738000	USD
CY2020Q1	us-gaap	Dividends Preferred Stock DividendsPreferredStock	3738000	USD
CY2021Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-7464000	USD
CY2020Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	114801000	USD
CY2021Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.11
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.51
CY2021Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.11
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.51
CY2021Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	69010000	shares
CY2020Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	75656000	shares
CY2021Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	74070000	shares
CY2020Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	80352000	shares
CY2021Q1	us-gaap	Profit Loss ProfitLoss	-3855000	USD
CY2020Q1	us-gaap	Profit Loss ProfitLoss	127114000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	51263000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	-50735000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-258000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-4534000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	51005000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-55269000	USD
CY2021Q1	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	47150000	USD
CY2020Q1	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	71845000	USD
CY2021Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	-129000	USD
CY2020Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	8575000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Noncontrolling Interest OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest	2655000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Noncontrolling Interest OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest	-2886000	USD
CY2021Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	44624000	USD
CY2020Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	66156000	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4935795000	USD
CY2021Q1	slg	Profit Loss Less Minority Interest In Net Income Loss Operating Partnerships ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships	-5225000	USD
CY2020Q1	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-12814000	USD
CY2021Q1	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	80310000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	48350000	USD
CY2021Q1	us-gaap	Dividends Preferred Stock DividendsPreferredStock	3738000	USD
CY2021Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	351000	USD
CY2021Q1	slg	Reallocationof Noncontrolling Interest In Operating Partnership Increase Decrease ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease	-26609000	USD
CY2021Q1	slg	Deferred Compensation Plan And Stock Award Net DeferredCompensationPlanAndStockAwardNet	6728000	USD
CY2021Q1	slg	Consolidation Of Joint Venture Interest ConsolidationOfJointVentureInterest	171000	USD
CY2021Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	110000	USD
CY2021Q1	us-gaap	Stock Issued During Period Value Stock Dividend StockIssuedDuringPeriodValueStockDividend	123529000	USD
CY2021Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.910
CY2021Q1	us-gaap	Dividends Common Stock DividendsCommonStock	63312000	USD
CY2021Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4935620000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5517198000	USD
CY2020Q1	slg	Profit Loss Less Minority Interest In Net Income Loss Operating Partnerships ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships	118246000	USD
CY2020Q1	us-gaap	Minority Interest Decrease From Redemptions MinorityInterestDecreaseFromRedemptions	1536000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-52383000	USD
CY2020Q1	us-gaap	Dividends Preferred Stock DividendsPreferredStock	3738000	USD
CY2020Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	166000	USD
CY2020Q1	us-gaap	Stock Issued During Period Value Conversion Of Units StockIssuedDuringPeriodValueConversionOfUnits	84000	USD
CY2020Q1	slg	Reallocationof Noncontrolling Interest In Operating Partnership Increase Decrease ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease	38529000	USD
CY2020Q1	slg	Deferred Compensation Plan And Stock Award Net DeferredCompensationPlanAndStockAwardNet	5502000	USD
CY2020Q1	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	219576000	USD
CY2020Q1	slg	Consolidation Of Joint Venture Interest ConsolidationOfJointVentureInterest	3814000	USD
CY2020Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	492000	USD
CY2020Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.304
CY2020Q1	us-gaap	Dividends Common Stock DividendsCommonStock	22665000	USD
CY2020Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5343965000	USD
CY2021Q1	us-gaap	Profit Loss ProfitLoss	-3855000	USD
CY2020Q1	us-gaap	Profit Loss ProfitLoss	127114000	USD
CY2021Q1	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	66770000	USD
CY2020Q1	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	70779000	USD
CY2021Q1	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-2864000	USD
CY2021Q1	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	69000	USD
CY2020Q1	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	108000	USD
CY2021Q1	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	-12629000	USD
CY2020Q1	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	0	USD
CY2021Q1	slg	Purchase Price Fair Value Adjustment Gain Loss PurchasePriceFairValueAdjustmentGainLoss	2664000	USD
CY2020Q1	slg	Purchase Price Fair Value Adjustment Gain Loss PurchasePriceFairValueAdjustmentGainLoss	0	USD
CY2021Q1	slg	Depreciable Real Estate Reserves And Impairment DepreciableRealEstateReservesAndImpairment	8241000	USD
CY2020Q1	slg	Depreciable Real Estate Reserves And Impairment DepreciableRealEstateReservesAndImpairment	0	USD
CY2021Q1	us-gaap	Gains Losses On Sales Of Investment Real Estate GainsLossesOnSalesOfInvestmentRealEstate	-1388000	USD
CY2020Q1	us-gaap	Gains Losses On Sales Of Investment Real Estate GainsLossesOnSalesOfInvestmentRealEstate	72636000	USD
CY2021Q1	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	0	USD
CY2020Q1	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	11248000	USD
CY2021Q1	us-gaap	Straight Line Rent StraightLineRent	2685000	USD
CY2020Q1	us-gaap	Straight Line Rent StraightLineRent	-3717000	USD
CY2021Q1	slg	Non Cash Lease Expense NonCashLeaseExpense	3375000	USD
CY2020Q1	slg	Non Cash Lease Expense NonCashLeaseExpense	3390000	USD
CY2021Q1	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-15564000	USD
CY2020Q1	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-1110000	USD
CY2021Q1	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	4138000	USD
CY2020Q1	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	44960000	USD
CY2021Q1	us-gaap	Increase Decrease In Due From Related Parties Current IncreaseDecreaseInDueFromRelatedPartiesCurrent	683000	USD
CY2020Q1	us-gaap	Increase Decrease In Due From Related Parties Current IncreaseDecreaseInDueFromRelatedPartiesCurrent	4711000	USD
CY2021Q1	us-gaap	Increase Decrease In Deferred Leasing Fees IncreaseDecreaseInDeferredLeasingFees	240000	USD
CY2020Q1	us-gaap	Increase Decrease In Deferred Leasing Fees IncreaseDecreaseInDeferredLeasingFees	8603000	USD
CY2021Q1	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	24354000	USD
CY2020Q1	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	48130000	USD
CY2021Q1	slg	Increase Decrease In Accrued Liabilities And Other IncreaseDecreaseInAccruedLiabilitiesAndOther	-38640000	USD
CY2020Q1	slg	Increase Decrease In Accrued Liabilities And Other IncreaseDecreaseInAccruedLiabilitiesAndOther	-13877000	USD
CY2021Q1	us-gaap	Increase Decrease In Deferred Liabilities IncreaseDecreaseInDeferredLiabilities	4121000	USD
CY2020Q1	us-gaap	Increase Decrease In Deferred Liabilities IncreaseDecreaseInDeferredLiabilities	7622000	USD
CY2021Q1	slg	Increase Decrease In Operating Lease Liability IncreaseDecreaseInOperatingLeaseLiability	-19160000	USD
CY2020Q1	slg	Increase Decrease In Operating Lease Liability IncreaseDecreaseInOperatingLeaseLiability	-2959000	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	18602000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	42026000	USD
CY2021Q1	us-gaap	Payments To Acquire Commercial Real Estate PaymentsToAcquireCommercialRealEstate	0	USD
CY2020Q1	us-gaap	Payments To Acquire Commercial Real Estate PaymentsToAcquireCommercialRealEstate	86846000	USD
CY2021Q1	slg	Payments To Acquire Land Buildings And Improvements PaymentsToAcquireLandBuildingsAndImprovements	49328000	USD
CY2020Q1	slg	Payments To Acquire Land Buildings And Improvements PaymentsToAcquireLandBuildingsAndImprovements	101726000	USD
CY2021Q1	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	21027000	USD
CY2020Q1	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	8906000	USD
CY2021Q1	slg	Proceeds From Equity Method Investment Dividends Or Distributions ProceedsFromEquityMethodInvestmentDividendsOrDistributions	19692000	USD
CY2020Q1	slg	Proceeds From Equity Method Investment Dividends Or Distributions ProceedsFromEquityMethodInvestmentDividendsOrDistributions	53516000	USD
CY2021Q1	us-gaap	Proceeds From Real Estate And Real Estate Joint Ventures ProceedsFromRealEstateAndRealEstateJointVentures	62800000	USD
CY2020Q1	us-gaap	Proceeds From Real Estate And Real Estate Joint Ventures ProceedsFromRealEstateAndRealEstateJointVentures	91156000	USD
CY2021Q1	slg	Proceeds From Consolidation Of Real Estate Investment ProceedsFromConsolidationOfRealEstateInvestment	9475000	USD
CY2020Q1	slg	Proceeds From Consolidation Of Real Estate Investment ProceedsFromConsolidationOfRealEstateInvestment	0	USD
CY2021Q1	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	4528000	USD
CY2020Q1	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	0	USD
CY2021Q1	slg	Payments For Proceeds From Other Investments PaymentsForProceedsFromOtherInvestments	54000	USD
CY2020Q1	slg	Payments For Proceeds From Other Investments PaymentsForProceedsFromOtherInvestments	4786000	USD
CY2021Q1	slg	Origination Of Debt And Preferred Equity Investments OriginationOfDebtAndPreferredEquityInvestments	5905000	USD
CY2020Q1	slg	Origination Of Debt And Preferred Equity Investments OriginationOfDebtAndPreferredEquityInvestments	223374000	USD
CY2021Q1	slg	Repayments Or Redemption Of Debt And Preferred Equity Investments RepaymentsOrRedemptionOfDebtAndPreferredEquityInvestments	0	USD
CY2020Q1	slg	Repayments Or Redemption Of Debt And Preferred Equity Investments RepaymentsOrRedemptionOfDebtAndPreferredEquityInvestments	151548000	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	20181000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-129418000	USD
CY2021Q1	us-gaap	Proceeds From Issuance Of Secured Debt ProceedsFromIssuanceOfSecuredDebt	10391000	USD
CY2020Q1	us-gaap	Proceeds From Issuance Of Secured Debt ProceedsFromIssuanceOfSecuredDebt	101103000	USD
CY2021Q1	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	362542000	USD
CY2020Q1	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	102777000	USD
CY2021Q1	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	530000000	USD
CY2020Q1	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	1125000000	USD
CY2021Q1	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	10000000	USD
CY2020Q1	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	315000000	USD
CY2021Q1	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	351000	USD
CY2021Q1	us-gaap	Payments For Repurchase Of Redeemable Preferred Stock PaymentsForRepurchaseOfRedeemablePreferredStock	3631000	USD
CY2020Q1	us-gaap	Payments For Repurchase Of Redeemable Preferred Stock PaymentsForRepurchaseOfRedeemablePreferredStock	19392000	USD
CY2020Q1	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	166000	USD
CY2021Q1	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	84089000	USD
CY2020Q1	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	219576000	USD
CY2021Q1	slg	Payments For Repurchase Of Partnership Units PaymentsForRepurchaseOfPartnershipUnits	13261000	USD
CY2020Q1	slg	Payments For Repurchase Of Partnership Units PaymentsForRepurchaseOfPartnershipUnits	18066000	USD
CY2021Q1	slg	Distributions To Noncontrolling Interests Other Partnerships DistributionsToNoncontrollingInterestsOtherPartnerships	110000	USD
CY2020Q1	slg	Distributions To Noncontrolling Interests Other Partnerships DistributionsToNoncontrollingInterestsOtherPartnerships	492000	USD
CY2021Q1	slg	Proceeds From Noncontrolling Interests In Other Partnerships ProceedsFromNoncontrollingInterestsInOtherPartnerships	171000	USD
CY2020Q1	slg	Proceeds From Noncontrolling Interests In Other Partnerships ProceedsFromNoncontrollingInterestsInOtherPartnerships	3814000	USD
CY2021Q1	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	0	USD
CY2020Q1	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	1536000	USD
CY2021Q1	slg	Distribution To Noncontrolling Interest Operating Partnership DistributionToNoncontrollingInterestOperatingPartnership	4148000	USD
CY2020Q1	slg	Distribution To Noncontrolling Interest Operating Partnership DistributionToNoncontrollingInterestOperatingPartnership	1284000	USD
CY2021Q1	us-gaap	Payments Of Dividends PaymentsOfDividends	69772000	USD
CY2020Q1	us-gaap	Payments Of Dividends PaymentsOfDividends	79662000	USD
CY2021Q1	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	2788000	USD
CY2020Q1	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	4752000	USD
CY2021Q1	slg	Deferred Loan Costs And Capitalized Lease Obligation DeferredLoanCostsAndCapitalizedLeaseObligation	288000	USD
CY2020Q1	slg	Deferred Loan Costs And Capitalized Lease Obligation DeferredLoanCostsAndCapitalizedLeaseObligation	562000	USD
CY2021Q1	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	255000	USD
CY2020Q1	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	0	USD
CY2021Q1	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-9971000	USD
CY2020Q1	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	466984000	USD
CY2021Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	28812000	USD
CY2020Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	379592000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	372795000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	241430000	USD
CY2021Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	401607000	USD
CY2020Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	621022000	USD
CY2021Q1	us-gaap	Partners Capital Account Redemptions PartnersCapitalAccountRedemptions	0	USD
CY2020Q1	us-gaap	Partners Capital Account Redemptions PartnersCapitalAccountRedemptions	84000	USD
CY2021Q1	slg	Issuance Of Special Dividend Stock Dividend IssuanceOfSpecialDividendStockDividend	123529000	USD
CY2020Q1	slg	Issuance Of Special Dividend Stock Dividend IssuanceOfSpecialDividendStockDividend	0	USD
CY2021Q1	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	15214000	USD
CY2020Q1	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	602000	USD
CY2021Q1	slg	Operating Partnership Noncontrolling Interest Fair Value Adjustment OperatingPartnershipNoncontrollingInterestFairValueAdjustment	26609000	USD
CY2020Q1	slg	Operating Partnership Noncontrolling Interest Fair Value Adjustment OperatingPartnershipNoncontrollingInterestFairValueAdjustment	0	USD
CY2021Q1	slg	Consolidation Of Real Estate Investment ConsolidationOfRealEstateInvestment	119444000	USD
CY2020Q1	slg	Consolidation Of Real Estate Investment ConsolidationOfRealEstateInvestment	0	USD
CY2021Q1	slg	Reversal Of Assets Held For Sale ReversalOfAssetsHeldForSale	0	USD
CY2020Q1	slg	Reversal Of Assets Held For Sale ReversalOfAssetsHeldForSale	391664000	USD
CY2021Q1	slg	Extinguishment Of Debt In Connection With Property Dispositions ExtinguishmentOfDebtInConnectionWithPropertyDispositions	53548000	USD
CY2020Q1	slg	Extinguishment Of Debt In Connection With Property Dispositions ExtinguishmentOfDebtInConnectionWithPropertyDispositions	0	USD
CY2021Q1	slg	Seller Financed Purchases SellerFinancedPurchases	0	USD
CY2020Q1	slg	Seller Financed Purchases SellerFinancedPurchases	100000000	USD
CY2021Q1	slg	Debt And Preferred Equity Reserves DebtAndPreferredEquityReserves	10000000	USD
CY2020Q1	slg	Debt And Preferred Equity Reserves DebtAndPreferredEquityReserves	4638000	USD
CY2021Q1	slg	Removalof Fully Depreciated Real Estate Assets RemovalofFullyDepreciatedRealEstateAssets	1120000	USD
CY2020Q1	slg	Removalof Fully Depreciated Real Estate Assets RemovalofFullyDepreciatedRealEstateAssets	512000	USD
CY2021Q1	slg	Share Repurchases Payable ShareRepurchasesPayable	3779000	USD
CY2020Q1	slg	Share Repurchases Payable ShareRepurchasesPayable	0	USD
CY2021Q1	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	119711000	USD
CY2020Q1	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	102782000	USD
CY2021Q1	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	304999000	USD
CY2020Q1	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	554195000	USD
CY2021Q1	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	96608000	USD
CY2020Q1	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	66827000	USD
CY2021Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	401607000	USD
CY2020Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	621022000	USD
CY2021Q1	slg	Numberof Real Estate Buildings NumberofRealEstateBuildings	65	building
CY2021Q1	us-gaap	Area Of Real Estate Property AreaOfRealEstateProperty	29134784	sqft
CY2021Q1	slg	Real Estate Weighted Average Occupancy RealEstateWeightedAverageOccupancy	0.922
CY2021Q1	slg	Mortgage Loanson Real Estate Commercialand Consumer Net Including Debt Investments Other MortgageLoansonRealEstateCommercialandConsumerNetIncludingDebtInvestmentsOther	1100000000	USD
CY2021Q1	slg	Debt Investments Other DebtInvestmentsOther	100000000	USD
CY2021Q1	slg	Number Of Shares On Redemption Of One Unit Of Partnership Interest NumberOfSharesOnRedemptionOfOneUnitOfPartnershipInterest	1	shares
CY2021Q1	slg	Rental Revenue Increase Decrease Acquired Lease Amortization RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization	1900000	USD
CY2020Q1	slg	Rental Revenue Increase Decrease Acquired Lease Amortization RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization	1200000	USD
CY2021Q1	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	239562000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	215673000	USD
CY2021Q1	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	204386000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	190523000	USD
CY2021Q1	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	35176000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	25150000	USD
CY2021Q1	slg	Finite Lived Intangible Liabilities Gross FiniteLivedIntangibleLiabilitiesGross	242334000	USD
CY2020Q4	slg	Finite Lived Intangible Liabilities Gross FiniteLivedIntangibleLiabilitiesGross	241409000	USD
CY2021Q1	slg	Finite Lived Intangible Liabilities Accumulated Amortization FiniteLivedIntangibleLiabilitiesAccumulatedAmortization	233766000	USD
CY2020Q4	slg	Finite Lived Intangible Liabilities Accumulated Amortization FiniteLivedIntangibleLiabilitiesAccumulatedAmortization	230479000	USD
CY2021Q1	slg	Finite Lived Intangible Liabilities Net FiniteLivedIntangibleLiabilitiesNet	8568000	USD
CY2020Q4	slg	Finite Lived Intangible Liabilities Net FiniteLivedIntangibleLiabilitiesNet	10930000	USD
CY2021Q1	slg	Net Intangible Assets Transferredto Assets Heldfor Sale NetIntangibleAssetsTransferredtoAssetsHeldforSale	0	USD
CY2020Q4	slg	Net Intangible Assets Transferredto Assets Heldfor Sale NetIntangibleAssetsTransferredtoAssetsHeldforSale	0	USD
CY2021Q1	slg	Net Intangible Liabilities Transferredto Liabilities Relatedto Assets Heldfor Sale NetIntangibleLiabilitiesTransferredtoLiabilitiesRelatedtoAssetsHeldforSale	0	USD
CY2020Q4	slg	Net Intangible Liabilities Transferredto Liabilities Relatedto Assets Heldfor Sale NetIntangibleLiabilitiesTransferredtoLiabilitiesRelatedtoAssetsHeldforSale	0	USD
CY2020Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1100000	USD
CY2021Q1	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	5000000.0	USD
CY2021Q1	slg	Debt Securities Available For Sale Number Of Securities Sold DebtSecuritiesAvailableForSaleNumberOfSecuritiesSold	1	security
CY2020Q1	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2021Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	700000	USD
CY2021Q1	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-bottom:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Use of Estimates</span></div><div style="margin-bottom:6pt;text-align:justify;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.</span></div>
CY2021Q1	us-gaap	Concentration Risk Credit Risk ConcentrationRiskCreditRisk	<div style="margin-bottom:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Concentrations of Credit Risk</span></div><div style="margin-bottom:6pt;text-align:justify;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash investments, debt and preferred equity investments and accounts receivable. We place our cash investments with high quality financial institutions. The collateral securing our debt and preferred equity investments is located in New York City. See Note 5, "Debt and Preferred Equity Investments." </span></div>We perform initial and ongoing evaluations of the credit quality of our tenants and require most tenants to provide security deposits or letters of credit. Though these security deposits and letters of credit are insufficient to meet the total value of a tenant's lease obligation, they are a measure of good faith and a potential source of funds to offset the economic costs associated with lost revenue from that tenant and the costs associated with re-tenanting a space.
CY2021Q1	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<div style="margin-bottom:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Reclassification</span></div><div style="margin-bottom:6pt;text-align:justify;text-indent:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Certain prior year balances have been reclassified to conform to our current year presentation.</span></div>
CY2020Q4	us-gaap	Mortgage Loans On Real Estate MortgageLoansOnRealEstate	1076542000	USD
CY2019Q4	us-gaap	Mortgage Loans On Real Estate MortgageLoansOnRealEstate	1580306000	USD
CY2021Q1	us-gaap	Mortgage Loans On Real Estate Amortization Of Premium MortgageLoansOnRealEstateAmortizationOfPremium	0	USD
CY2020	us-gaap	Mortgage Loans On Real Estate Amortization Of Premium MortgageLoansOnRealEstateAmortizationOfPremium	1048643000	USD
CY2021Q1	slg	Sec Schedule1229 Real Estate Companies Investment In Mortgage Loans On Real Estate Loan Loss Reserve Period Increase Decrease SECSchedule1229RealEstateCompaniesInvestmentInMortgageLoansOnRealEstateLoanLossReservePeriodIncreaseDecrease	0	USD
CY2020	slg	Sec Schedule1229 Real Estate Companies Investment In Mortgage Loans On Real Estate Loan Loss Reserve Period Increase Decrease SECSchedule1229RealEstateCompaniesInvestmentInMortgageLoansOnRealEstateLoanLossReservePeriodIncreaseDecrease	-11463000	USD
CY2021Q1	us-gaap	Mortgage Loans On Real Estate MortgageLoansOnRealEstate	1097202000	USD
CY2020Q4	us-gaap	Mortgage Loans On Real Estate MortgageLoansOnRealEstate	1076542000	USD
CY2021Q1	us-gaap	Mortgage Loans On Real Estate Commercial And Consumer Net MortgageLoansOnRealEstateCommercialAndConsumerNet	1097202000	USD
CY2021Q1	slg	Mortgage Loanson Real Estate Senior Financing MortgageLoansonRealEstateSeniorFinancing	6565960000	USD
CY2020Q4	us-gaap	Allowance For Loan And Lease Losses Real Estate AllowanceForLoanAndLeaseLossesRealEstate	13213000	USD
CY2019Q4	us-gaap	Allowance For Loan And Lease Losses Real Estate AllowanceForLoanAndLeaseLossesRealEstate	1750000	USD
CY2021Q1	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	20693000	USD
CY2021Q1	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	0	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	37033000	USD
CY2021Q1	us-gaap	Allowance For Loan And Lease Losses Real Estate AllowanceForLoanAndLeaseLossesRealEstate	13213000	USD
CY2020Q4	us-gaap	Allowance For Loan And Lease Losses Real Estate AllowanceForLoanAndLeaseLossesRealEstate	13213000	USD
CY2021Q1	slg	Financing Receivable Nonaccrual No Allowance Number FinancingReceivableNonaccrualNoAllowanceNumber	1	loan
CY2021Q1	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	225400000	USD
CY2021Q1	slg	Number Of Investments Nonperforming NumberOfInvestmentsNonperforming	1	investment
CY2021Q1	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	27700000	USD
CY2021Q1	us-gaap	Notes Receivable Gross NotesReceivableGross	1097202000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	1076542000	USD
CY2021Q1	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	0	USD
CY2021Q1	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	361444000	USD
CY2021Q1	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	297924000	USD
CY2021Q1	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	437834000	USD
CY2021Q1	us-gaap	Notes Receivable Gross NotesReceivableGross	1097202000	USD
CY2021Q1	slg	Financing Receivable Portfolio Segments Number FinancingReceivablePortfolioSegmentsNumber	1	segment
CY2020	slg	Financing Receivable Portfolio Segments Number FinancingReceivablePortfolioSegmentsNumber	1	segment
CY2021Q1	slg	Financing Receivable Recorded In Other Assets FinancingReceivableRecordedInOtherAssets	66400000	USD
CY2020Q4	slg	Financing Receivable Recorded In Other Assets FinancingReceivableRecordedInOtherAssets	66200000	USD
CY2021Q1	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0.0	USD
CY2020Q1	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	2800000	USD
CY2021Q1	srt	Mortgage Loans On Real Estate Interest Rate MortgageLoansOnRealEstateInterestRate	0.0590
CY2021Q1	slg	Variable Interest Entity Not Primary Beneficiary Investment VariableInterestEntityNotPrimaryBeneficiaryInvestment	132700000	USD
CY2020Q4	slg	Variable Interest Entity Not Primary Beneficiary Investment VariableInterestEntityNotPrimaryBeneficiaryInvestment	134000000.0	USD
CY2020Q4	us-gaap	Equity Method Investments EquityMethodInvestments	3823322000	USD
CY2021Q1	us-gaap	Equity Method Investment Difference Between Carrying Amount And Underlying Equity EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity	174200000	USD
CY2021Q1	us-gaap	Deferred Costs Leasing Gross DeferredCostsLeasingGross	448197000	USD
CY2020Q4	us-gaap	Deferred Costs Leasing Gross DeferredCostsLeasingGross	447002000	USD
CY2021Q1	slg	Accumulated Amortization Of Deferred Costs AccumulatedAmortizationOfDeferredCosts	277945000	USD
CY2020Q4	slg	Accumulated Amortization Of Deferred Costs AccumulatedAmortizationOfDeferredCosts	269834000	USD
CY2021Q1	us-gaap	Deferred Costs Current And Noncurrent DeferredCostsCurrentAndNoncurrent	170252000	USD
CY2020Q4	us-gaap	Deferred Costs Current And Noncurrent DeferredCostsCurrentAndNoncurrent	177168000	USD
CY2021Q1	slg	Secured Debt Bearing Fixed Interest Amount SecuredDebtBearingFixedInterestAmount	1081142000	USD
CY2020Q4	slg	Secured Debt Bearing Fixed Interest Amount SecuredDebtBearingFixedInterestAmount	1083683000	USD
CY2021Q1	slg	Secured Debt Bearing Variable Interest Amount SecuredDebtBearingVariableInterestAmount	786521000	USD
CY2020Q4	slg	Secured Debt Bearing Variable Interest Amount SecuredDebtBearingVariableInterestAmount	917677000	USD
CY2021Q1	slg	Secured Debt Gross SecuredDebtGross	1867663000	USD
CY2020Q4	slg	Secured Debt Gross SecuredDebtGross	2001360000	USD
CY2021Q1	slg	Secured Debt Deferred Finance Costs Net SecuredDebtDeferredFinanceCostsNet	18962000	USD
CY2020Q4	slg	Secured Debt Deferred Finance Costs Net SecuredDebtDeferredFinanceCostsNet	21388000	USD
CY2021Q1	us-gaap	Secured Debt SecuredDebt	1848701000	USD
CY2020Q4	us-gaap	Secured Debt SecuredDebt	1979972000	USD
CY2021Q1	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	2400000000	USD
CY2020Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	2500000000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal Remainder Of Fiscal Year LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear	526901000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	1064200000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	2496594000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	478029000	USD
CY2021Q1	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	100823000	USD
CY2021Q1	slg	Long Term Debt Maturity After Year Four LongTermDebtMaturityAfterYearFour	681116000	USD
CY2021Q1	slg	Long Term Debt Maturities Repayments Of Principal LongTermDebtMaturitiesRepaymentsOfPrincipal	5347663000	USD
CY2021Q1	us-gaap	Interest Expense InterestExpense	39868000	USD
CY2020Q1	us-gaap	Interest Expense InterestExpense	56813000	USD
CY2021Q1	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	1492000	USD
CY2020Q1	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	1663000	USD
CY2021Q1	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	17583000	USD
CY2020Q1	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	20483000	USD
CY2021Q1	us-gaap	Interest Income Operating InterestIncomeOperating	389000	USD
CY2020Q1	us-gaap	Interest Income Operating InterestIncomeOperating	499000	USD
CY2021Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-23388000	USD
CY2020Q1	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-37494000	USD
CY2021Q1	us-gaap	Due From Joint Ventures DueFromJointVentures	26500000	USD
CY2020Q4	us-gaap	Due From Joint Ventures DueFromJointVentures	27006000	USD
CY2021Q1	us-gaap	Due From Other Related Parties DueFromOtherRelatedParties	7810000	USD
CY2020Q4	us-gaap	Due From Other Related Parties DueFromOtherRelatedParties	7651000	USD
CY2021Q1	us-gaap	Due From Related Parties DueFromRelatedParties	34310000	USD
CY2020Q4	us-gaap	Due From Related Parties DueFromRelatedParties	34657000	USD
CY2021Q1	slg	Total Shares Authorized TotalSharesAuthorized	260000000	shares
CY2021Q1	slg	Total Par Or Stated Value Per Share TotalParOrStatedValuePerShare	0.01
CY2021Q1	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	160000000	shares
CY2021Q1	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2021Q1	us-gaap	Excess Stock Shares Authorized ExcessStockSharesAuthorized	75000000	shares
CY2021Q1	slg	Excess Stock Par Or Stated Value Per Share ExcessStockParOrStatedValuePerShare	0.01
CY2021Q1	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	25000000	shares
CY2021Q1	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2021Q1	us-gaap	Excess Stock Shares Issued ExcessStockSharesIssued	0	shares
CY2017	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	8105881	shares
CY2017	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	104.61
CY2018	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	9468617	shares
CY2018	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	99.03
CY2019	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	4465857	shares
CY2019	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	86.06
CY2020	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	8529279	shares
CY2020	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	62.39
CY2021Q1	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	1306460	shares
CY2021Q1	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	61.46
CY2021Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-7464000	USD
CY2020Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	114801000	USD
CY2021Q1	us-gaap	Distributed Earnings DistributedEarnings	371000	USD
CY2020Q1	us-gaap	Distributed Earnings DistributedEarnings	113000	USD
CY2021Q1	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	0	USD
CY2020Q1	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	464000	USD
CY2021Q1	slg	Net Income Loss Available To Common Stockholders After Distributed And Undistributed Earnings Allocation Basic NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic	-7835000	USD
CY2020Q1	slg	Net Income Loss Available To Common Stockholders After Distributed And Undistributed Earnings Allocation Basic NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic	114224000	USD
CY2021Q1	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	-371000	USD
CY2020Q1	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	-113000	USD
CY2021Q1	slg	Distributed Earnings Diluted DistributedEarningsDiluted	0	USD
CY2020Q1	slg	Distributed Earnings Diluted DistributedEarningsDiluted	-464000	USD
CY2021Q1	us-gaap	Dilutive Securities Effect On Basic Earnings Per Share Other DilutiveSecuritiesEffectOnBasicEarningsPerShareOther	-476000	USD
CY2020Q1	us-gaap	Dilutive Securities Effect On Basic Earnings Per Share Other DilutiveSecuritiesEffectOnBasicEarningsPerShareOther	6202000	USD
CY2021Q1	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-7940000	USD
CY2020Q1	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	121003000	USD
CY2021Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	69010000	shares
CY2020Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	75656000	shares
CY2021Q1	slg	Incremental Common Shares Attributable To Redemption Of Units To Common Shares IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares	4148000	shares
CY2020Q1	slg	Incremental Common Shares Attributable To Redemption Of Units To Common Shares IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares	4220000	shares
CY2021Q1	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	595000	shares
CY2020Q1	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	476000	shares
CY2021Q1	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	317000	shares
CY2020Q1	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	0	shares
CY2021Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	74070000	shares
CY2020Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	80352000	shares
CY2021Q1	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1159343	shares
CY2021Q1	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	500000	USD
CY2020Q1	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	600000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	42548000	USD
CY2021Q1	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-5802000	USD
CY2021Q1	slg	Other Comprehensive Income Loss Deferred Net Lossfrom Terminated Hedges OtherComprehensiveIncomeLossDeferredNetLossfromTerminatedHedges	-600000	USD
CY2020Q4	slg	Other Comprehensive Income Loss Deferred Net Lossfrom Terminated Hedges OtherComprehensiveIncomeLossDeferredNetLossfromTerminatedHedges	-500000	USD
CY2021Q1	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	23784000	USD
CY2021Q1	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	365000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	28570000	USD
CY2020Q4	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	28000	USD
CY2020Q1	slg	Accumulated Other Comprehensive Income Loss Gain Lossfrom Changesin Fair Value AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue	0	USD
CY2021Q1	slg	Accumulated Other Comprehensive Income Loss Gain Lossfrom Changesin Fair Value AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue	0	USD
CY2021Q1	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	48300000	USD
CY2021Q1	us-gaap	Assets Needed For Immediate Settlement Aggregate Fair Value AssetsNeededForImmediateSettlementAggregateFairValue	49000000.0	USD
CY2021Q1	us-gaap	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	16600000	USD
CY2021Q1	slg	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months Into Equity In Net Income CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonthsIntoEquityInNetIncome	2200000	USD
CY2021Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	45175000	USD
CY2020Q1	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	-52171000	USD
CY2021Q1	us-gaap	Interest Rate Cash Flow Hedge Gain Loss Reclassified To Earnings Net InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet	6088000	USD
CY2020Q1	us-gaap	Interest Rate Cash Flow Hedge Gain Loss Reclassified To Earnings Net InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet	1436000	USD
CY2021Q1	us-gaap	Operating Lease Lease Income Lease Payments OperatingLeaseLeaseIncomeLeasePayments	164679000	USD
CY2020Q1	us-gaap	Operating Lease Lease Income Lease Payments OperatingLeaseLeaseIncomeLeasePayments	194224000	USD
CY2021Q1	us-gaap	Operating Lease Variable Lease Income OperatingLeaseVariableLeaseIncome	25279000	USD
CY2020Q1	us-gaap	Operating Lease Variable Lease Income OperatingLeaseVariableLeaseIncome	27168000	USD
CY2021Q1	slg	Operating Lease Lease Income Fixed And Variable Lease Payments OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments	189958000	USD
CY2020Q1	slg	Operating Lease Lease Income Fixed And Variable Lease Payments OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments	221392000	USD
CY2021Q1	us-gaap	Amortization Of Above And Below Market Leases AmortizationOfAboveAndBelowMarketLeases	-1869000	USD
CY2020Q1	us-gaap	Amortization Of Above And Below Market Leases AmortizationOfAboveAndBelowMarketLeases	1239000	USD
CY2021Q1	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	188089000	USD
CY2020Q1	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	222631000	USD
CY2021Q1	us-gaap	Sublease Income SubleaseIncome	65800000	USD
CY2020Q1	us-gaap	Sublease Income SubleaseIncome	66300000	USD
CY2021Q1	us-gaap	Sales Type Lease Interest Income SalesTypeLeaseInterestIncome	1101000	USD
CY2020Q1	us-gaap	Sales Type Lease Interest Income SalesTypeLeaseInterestIncome	0	USD
CY2021Q1	slg	Operating Leases Minimum Lease Term OperatingLeasesMinimumLeaseTerm	P1Y
CY2021Q1	us-gaap	Finance Lease Liability Payments Remainder Of Fiscal Year FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear	31136000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Remainder Of Fiscal Year LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear	31954000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due Next Twelve Months FinanceLeaseLiabilityPaymentsDueNextTwelveMonths	3522000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	29386000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	3570000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	29502000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	3641000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	30545000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	3810000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	30772000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	3858000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	30911000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due After Year Five FinanceLeaseLiabilityPaymentsDueAfterYearFive	256692000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	631532000	USD
CY2021Q1	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	306229000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	814602000	USD
CY2021Q1	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	153607000	USD
CY2021Q1	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	359217000	USD
CY2021Q1	us-gaap	Finance Lease Liability FinanceLeaseLiability	152622000	USD
CY2021Q1	us-gaap	Operating Lease Liability OperatingLeaseLiability	455385000	USD
CY2021Q1	slg	Operating Lease Cost Before Capitalized Operating Lease Costs OperatingLeaseCostBeforeCapitalizedOperatingLeaseCosts	7567000	USD
CY2020Q1	slg	Operating Lease Cost Before Capitalized Operating Lease Costs OperatingLeaseCostBeforeCapitalizedOperatingLeaseCosts	8113000	USD
CY2021Q1	slg	Operating Lease Cost Capitalized OperatingLeaseCostCapitalized	828000	USD
CY2020Q1	slg	Operating Lease Cost Capitalized OperatingLeaseCostCapitalized	746000	USD
CY2021Q1	us-gaap	Operating Lease Cost OperatingLeaseCost	6739000	USD
CY2020Q1	us-gaap	Operating Lease Cost OperatingLeaseCost	7367000	USD
CY2021Q1	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	1492000	USD
CY2020Q1	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	1663000	USD
CY2021Q1	slg	Finance Lease Interest Expense Capitalized FinanceLeaseInterestExpenseCapitalized	0	USD
CY2020Q1	slg	Finance Lease Interest Expense Capitalized FinanceLeaseInterestExpenseCapitalized	747000	USD
CY2021Q1	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	1492000	USD
CY2020Q1	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	916000	USD
CY2021Q1	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	180000	USD
CY2020Q1	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	305000	USD
CY2021Q1	slg	Finance Lease Cost FinanceLeaseCost	1672000	USD
CY2020Q1	slg	Finance Lease Cost FinanceLeaseCost	1221000	USD
CY2021Q1	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0452
CY2021Q1	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P27Y
CY2021Q1	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	2	segment
CY2021Q1	us-gaap	Revenues Revenues	226102000	USD
CY2020Q1	us-gaap	Revenues Revenues	314303000	USD
CY2021Q1	slg	Income Loss From Continuing Operations Before Realized Gain Loss On Disposal Of Equity Method Investment IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment	-3855000	USD
CY2020Q1	slg	Income Loss From Continuing Operations Before Realized Gain Loss On Disposal Of Equity Method Investment IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment	127114000	USD
CY2021Q1	us-gaap	Assets Assets	12044045000	USD
CY2020Q4	us-gaap	Assets Assets	11707567000	USD
CY2021Q1	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	22900000	USD
CY2020Q1	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	19600000	USD

Files In Submission

Name	View Source	Status
0001040971-21-000017-index-headers.html	Edgar Link	pending
0001040971-21-000017-index.html	Edgar Link	pending
0001040971-21-000017.txt	Edgar Link	pending
0001040971-21-000017-xbrl.zip	Edgar Link	pending
a21q110qex311.htm	Edgar Link	pending
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FilingSummary.xml	Edgar Link	unprocessable
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
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report.css	Edgar Link	pending
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slg-20210331.htm	Edgar Link	pending
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slg-20210331_cal.xml	Edgar Link	unprocessable
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slg-20210331_htm.xml	Edgar Link	completed
slg-20210331_lab.xml	Edgar Link	unprocessable
slg-20210331_pre.xml	Edgar Link	unprocessable

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$SLG
SL Green Realty Corp Stock $slg

2021 Q1 Form 10-Q Financial Statement

#000104097121000017 Filed on May 10, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SLG SL Green Realty Corp Stock $slg

2021 Q1 Form 10-Q Financial Statement

#000104097121000017 Filed on May 10, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SLG
SL Green Realty Corp Stock $slg