$SLG
SL Green Realty Corp Stock $slg

$slg Overview Financials Valuation SEC Filings Company Website

2021 Q4 Form 10-Q Financial Statement

#000104097121000034 Filed on November 09, 2021

Income Statement

Concept	2021 Q4	2021 Q3	2020 Q3
Revenue	$194.6M	$205.2M	$249.8M
YoY Change	-17.16%	-17.87%	-20.34%
Cost Of Revenue	$78.37M	$79.38M	$96.40M
YoY Change	-16.54%	-17.66%	-18.17%
Gross Profit	$116.2M	$125.8M	$153.4M
YoY Change	-17.58%	-17.98%	-21.69%
Gross Profit Margin	59.72%	61.32%	61.4%
Selling, General & Admin	$30.04M	$23.50M	$23.60M
YoY Change	19.22%	-0.42%	-0.84%
% of Gross Profit	25.85%	18.68%	15.38%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$49.25M	$51.62M	$95.60M
YoY Change	-18.59%	-46.0%	30.07%
% of Gross Profit	42.38%	41.03%	62.32%
Operating Expenses	$80.31M	$23.50M	$23.60M
YoY Change	-11.16%	-0.42%	-0.84%
Operating Profit	$35.90M	$102.3M	$129.8M
YoY Change	-29.05%	-21.17%	-24.58%
Interest Expense	-$66.51M	$34.05M	$42.60M
YoY Change	-143.84%	-20.05%	-33.03%
% of Operating Profit	-185.27%	33.28%	32.82%
Other Income/Expense, Net	-$18.10M	$0.00	-$6.600M
YoY Change	-66.36%	-100.0%	-5.71%
Pretax Income	-$48.18M	$415.5M	$20.70M
YoY Change	-124.05%	1907.41%	-49.14%
Income Tax		$0.00	$0.00
% Of Pretax Income		0.0%	0.0%
Net Earnings	-$45.72M	$391.9M	$17.60M
YoY Change	-125.89%	2127.33%	-52.31%
Net Earnings / Revenue	-23.5%	191.0%	7.04%
Basic Earnings Per Share		$5.77	$0.19
Diluted Earnings Per Share	-$810.5K	$5.75	$0.19
COMMON SHARES
Basic Shares Outstanding	66.73M shares	66.84M shares	70.94M shares
Diluted Shares Outstanding		71.49M shares	75.41M shares

Balance Sheet

Concept	2021 Q4	2021 Q3	2020 Q3
SHORT-TERM ASSETS
Cash & Short-Term Investments	$286.2M	$292.4M	$249.1M
YoY Change	-2.87%	17.35%	63.95%
Cash & Equivalents	$251.4M	$257.9M	$221.4M
Short-Term Investments	$34.75M	$34.43M	$27.73M
Other Short-Term Assets
YoY Change
Inventory	$140.9M		$0.00
Prepaid Expenses
Receivables	$325.3M	$334.9M	$409.0M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$717.6M	$592.9M	$630.0M
YoY Change	10.74%	-5.9%	-29.69%
LONG-TERM ASSETS
Property, Plant & Equipment	$5.755B	$5.588B	$6.761B
YoY Change	6.59%	-17.34%	-2.59%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments	$2.998B	$3.028B	$2.947B
YoY Change	-21.59%	2.76%	0.79%
Other Assets	$210.1M	$212.6M	$289.0M
YoY Change	-26.03%	-26.43%	4.33%
Total Long-Term Assets	$10.35B	$10.26B	$11.69B
YoY Change	-6.42%	-12.24%	-5.69%
TOTAL ASSETS
Total Short-Term Assets	$717.6M	$592.9M	$630.0M
Total Long-Term Assets	$10.35B	$10.26B	$11.69B
Total Assets	$11.07B	$10.86B	$12.32B
YoY Change	-5.47%	-11.91%	-7.3%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$157.6M	$137.9M	$153.0M
YoY Change	4.35%	-9.84%	6.99%
Accrued Expenses	$864.1M	$458.1M	$382.0M
YoY Change	144.09%	19.93%	-7.28%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$1.261B	$674.4M	$617.0M
YoY Change	78.15%	9.3%	-11.35%
LONG-TERM LIABILITIES
Long-Term Debt	$4.120B	$4.260B	$5.594B
YoY Change	-18.91%	-23.85%	-4.86%
Other Long-Term Liabilities	$366.8M	$277.9M	$424.0M
YoY Change	-12.88%	-34.45%	58.8%
Total Long-Term Liabilities	$4.487B	$4.538B	$6.018B
YoY Change	-18.45%	-24.59%	-2.1%
TOTAL LIABILITIES
Total Short-Term Liabilities	$1.261B	$674.4M	$617.0M
Total Long-Term Liabilities	$4.487B	$4.538B	$6.018B
Total Liabilities	$5.748B	$5.212B	$6.634B
YoY Change	-7.46%	-21.43%	-3.06%
SHAREHOLDERS EQUITY
Retained Earnings	$975.8M	$1.258B	$1.035B
YoY Change	-3.91%	21.55%	-15.56%
Common Stock	$672.0K	$680.0K	$741.0K
YoY Change	-6.15%	-8.23%	-10.29%
Preferred Stock
YoY Change
Treasury Stock (at cost)	$126.2M	$126.2M	$124.0M
YoY Change	1.7%	1.7%	0.0%
Treasury Stock Shares	1.027M shares	1.061M shares	1.055M shares
Shareholders Equity	$4.765B	$5.068B	$5.056B
YoY Change
Total Liabilities & Shareholders Equity	$11.07B	$10.86B	$12.32B
YoY Change	-5.47%	-11.91%	-7.3%

Cashflow Statement

Concept	2021 Q4	2021 Q3	2020 Q3
OPERATING ACTIVITIES
Net Income	-$45.72M	$391.9M	$17.60M
YoY Change	-125.89%	2127.33%	-52.31%
Depreciation, Depletion And Amortization	$49.25M	$51.62M	$95.60M
YoY Change	-18.59%	-46.0%	30.07%
Cash From Operating Activities	$64.97M	$87.75M	$103.6M
YoY Change	-71.29%	-15.3%	27.12%
INVESTING ACTIVITIES
Capital Expenditures	-$94.11M	-$214.4M	-$98.40M
YoY Change	-46.68%	117.89%	72.93%
Acquisitions
YoY Change
Other Investing Activities	$200.8M	$459.8M	$69.50M
YoY Change	-76.59%	561.53%	-75.39%
Cash From Investing Activities	$106.7M	$245.4M	-$28.80M
YoY Change	-84.34%	-951.93%	-112.77%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-180.6M	-303.7M	-871.6M
YoY Change	-78.48%	-65.16%	162.85%
NET CHANGE
Cash From Operating Activities	64.97M	87.75M	103.6M
Cash From Investing Activities	106.7M	245.4M	-28.80M
Cash From Financing Activities	-180.6M	-303.7M	-871.6M
Net Change In Cash	-8.949M	29.43M	-796.8M
YoY Change	-113.1%	-103.69%	3139.02%
FREE CASH FLOW
Cash From Operating Activities	$64.97M	$87.75M	$103.6M
Capital Expenditures	-$94.11M	-$214.4M	-$98.40M
Free Cash Flow	$159.1M	$302.2M	$202.0M
YoY Change	-60.51%	49.58%	45.95%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2021
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Entity Central Index Key EntityCentralIndexKey	0001040971
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
	dei	Amendment Flag AmendmentFlag	false
CY2019	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201613Member
CY2019	us-gaap	Accounting Standards Update Extensible List AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201613Member
	dei	Document Type DocumentType	10-Q
	dei	Document Quarterly Report DocumentQuarterlyReport	true
	dei	Document Period End Date DocumentPeriodEndDate	2021-09-30
	dei	Document Transition Report DocumentTransitionReport	false
	dei	Entity File Number EntityFileNumber	1-13199
	dei	Entity Registrant Name EntityRegistrantName	SL GREEN REALTY CORP
	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	MD
	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	13-3956775
	dei	Entity Address Address Line1 EntityAddressAddressLine1	One Vanderbilt Avenue
	dei	Entity Address City Or Town EntityAddressCityOrTown	New York
	dei	Entity Address State Or Province EntityAddressStateOrProvince	NY
	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	10017
	dei	City Area Code CityAreaCode	212
	dei	Local Phone Number LocalPhoneNumber	594-2700
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
	dei	Entity Small Business EntitySmallBusiness	false
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Shell Company EntityShellCompany	false
CY2021Q4	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	66726676	shares
CY2021Q3	us-gaap	Land Land	1489101000	USD
CY2020Q4	us-gaap	Land Land	1315832000	USD
CY2021Q3	us-gaap	Investment Building And Building Improvements InvestmentBuildingAndBuildingImprovements	3828052000	USD
CY2020Q4	us-gaap	Investment Building And Building Improvements InvestmentBuildingAndBuildingImprovements	4168193000	USD
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CY2021Q3	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	498416000	USD
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CY2021Q3	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	27445000	USD
CY2020Q4	us-gaap	Finance Lease Right Of Use Asset FinanceLeaseRightOfUseAsset	55711000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	367209000	USD
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CY2020Q4	us-gaap	Real Estate Investment Property At Cost RealEstateInvestmentPropertyAtCost	7355079000	USD
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CY2020Q4	us-gaap	Marketable Securities MarketableSecurities	28570000	USD
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CY2021Q3	slg	Discount Of Structured Finance Investments DiscountOfStructuredFinanceInvestments	6494000	USD
CY2020Q4	slg	Discount Of Structured Finance Investments DiscountOfStructuredFinanceInvestments	11232000	USD
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CY2020Q3	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	8957000	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	0	USD
	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	27018000	USD
CY2021Q3	slg	Transaction Related Costs TransactionRelatedCosts	190000	USD
CY2020Q3	slg	Transaction Related Costs TransactionRelatedCosts	45000	USD
	slg	Transaction Related Costs TransactionRelatedCosts	215000	USD
	slg	Transaction Related Costs TransactionRelatedCosts	483000	USD
CY2021Q3	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	23477000	USD
CY2020Q3	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	23602000	USD
	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	68426000	USD
	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	66682000	USD
CY2021Q3	slg	Total Costs And Expenses Including Nonoperating Income Expense TotalCostsAndExpensesIncludingNonoperatingIncomeExpense	169476000	USD
CY2020Q3	slg	Total Costs And Expenses Including Nonoperating Income Expense TotalCostsAndExpensesIncludingNonoperatingIncomeExpense	248212000	USD
	slg	Total Costs And Expenses Including Nonoperating Income Expense TotalCostsAndExpensesIncludingNonoperatingIncomeExpense	573007000	USD
	slg	Total Costs And Expenses Including Nonoperating Income Expense TotalCostsAndExpensesIncludingNonoperatingIncomeExpense	744980000	USD
CY2021Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-15487000	USD
CY2020Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-432000	USD
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-31321000	USD
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-15445000	USD
CY2021Q3	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	-1280000	USD
CY2020Q3	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	0	USD
	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	-5438000	USD
	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	0	USD
CY2021Q3	slg	Purchase Price Fair Value Adjustment Gross PurchasePriceFairValueAdjustmentGross	208810000	USD
CY2020Q3	slg	Purchase Price Fair Value Adjustment Gross PurchasePriceFairValueAdjustmentGross	0	USD
	slg	Purchase Price Fair Value Adjustment Gross PurchasePriceFairValueAdjustmentGross	209527000	USD
	slg	Purchase Price Fair Value Adjustment Gross PurchasePriceFairValueAdjustmentGross	0	USD
CY2021Q3	us-gaap	Gains Losses On Sales Of Investment Real Estate GainsLossesOnSalesOfInvestmentRealEstate	187766000	USD
CY2020Q3	us-gaap	Gains Losses On Sales Of Investment Real Estate GainsLossesOnSalesOfInvestmentRealEstate	26104000	USD
	us-gaap	Gains Losses On Sales Of Investment Real Estate GainsLossesOnSalesOfInvestmentRealEstate	285338000	USD
	us-gaap	Gains Losses On Sales Of Investment Real Estate GainsLossesOnSalesOfInvestmentRealEstate	163624000	USD
CY2021Q3	slg	Depreciable Real Estate Reserves And Impairment DepreciableRealEstateReservesAndImpairment	0	USD
CY2020Q3	slg	Depreciable Real Estate Reserves And Impairment DepreciableRealEstateReservesAndImpairment	6627000	USD
	slg	Depreciable Real Estate Reserves And Impairment DepreciableRealEstateReservesAndImpairment	5696000	USD
	slg	Depreciable Real Estate Reserves And Impairment DepreciableRealEstateReservesAndImpairment	6627000	USD
CY2021Q3	us-gaap	Profit Loss ProfitLoss	415534000	USD
CY2020Q3	us-gaap	Profit Loss ProfitLoss	20677000	USD
	us-gaap	Profit Loss ProfitLoss	528813000	USD
	us-gaap	Profit Loss ProfitLoss	214418000	USD
CY2021Q3	us-gaap	Noncontrolling Interest In Net Income Loss Operating Partnerships Redeemable NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable	22683000	USD
CY2020Q3	us-gaap	Noncontrolling Interest In Net Income Loss Operating Partnerships Redeemable NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable	802000	USD
	us-gaap	Noncontrolling Interest In Net Income Loss Operating Partnerships Redeemable NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable	28489000	USD
	us-gaap	Noncontrolling Interest In Net Income Loss Operating Partnerships Redeemable NoncontrollingInterestInNetIncomeLossOperatingPartnershipsRedeemable	10073000	USD
CY2021Q3	us-gaap	Noncontrolling Interest In Net Income Loss Other Noncontrolling Interests Redeemable NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable	-915000	USD
CY2020Q3	us-gaap	Noncontrolling Interest In Net Income Loss Other Noncontrolling Interests Redeemable NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable	414000	USD
	us-gaap	Noncontrolling Interest In Net Income Loss Other Noncontrolling Interests Redeemable NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable	-2454000	USD
	us-gaap	Noncontrolling Interest In Net Income Loss Other Noncontrolling Interests Redeemable NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsRedeemable	1145000	USD
CY2021Q3	us-gaap	Noncontrolling Interest In Net Income Loss Preferred Unit Holders Redeemable NoncontrollingInterestInNetIncomeLossPreferredUnitHoldersRedeemable	1823000	USD
CY2020Q3	us-gaap	Noncontrolling Interest In Net Income Loss Preferred Unit Holders Redeemable NoncontrollingInterestInNetIncomeLossPreferredUnitHoldersRedeemable	1864000	USD
	us-gaap	Noncontrolling Interest In Net Income Loss Preferred Unit Holders Redeemable NoncontrollingInterestInNetIncomeLossPreferredUnitHoldersRedeemable	5492000	USD
	us-gaap	Noncontrolling Interest In Net Income Loss Preferred Unit Holders Redeemable NoncontrollingInterestInNetIncomeLossPreferredUnitHoldersRedeemable	6883000	USD
CY2021Q3	us-gaap	Net Income Loss NetIncomeLoss	391943000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	17597000	USD
	us-gaap	Net Income Loss NetIncomeLoss	497286000	USD
	us-gaap	Net Income Loss NetIncomeLoss	196317000	USD
CY2021Q3	us-gaap	Dividends Preferred Stock DividendsPreferredStock	3738000	USD
CY2020Q3	us-gaap	Dividends Preferred Stock DividendsPreferredStock	3738000	USD
	us-gaap	Dividends Preferred Stock DividendsPreferredStock	11213000	USD
	us-gaap	Dividends Preferred Stock DividendsPreferredStock	11213000	USD
CY2021Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	388205000	USD
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	13859000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	486073000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	185104000	USD
CY2021Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	5.77
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.19
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	7.08
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.51
CY2021Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	5.75
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.19
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	7.04
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.50
CY2021Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	66840000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70943000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	68275000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	73373000	shares
CY2021Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	71487000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	75414000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	73087000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	77937000	shares
CY2021Q3	us-gaap	Profit Loss ProfitLoss	415534000	USD
CY2020Q3	us-gaap	Profit Loss ProfitLoss	20677000	USD
	us-gaap	Profit Loss ProfitLoss	528813000	USD
	us-gaap	Profit Loss ProfitLoss	214418000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	6615000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	6099000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	6565000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax	-48227000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	66000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	389000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	314000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-2152000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	6681000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	6488000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	6879000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-50379000	USD
CY2021Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	422215000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	27165000	USD
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	535692000	USD
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	164039000	USD
CY2021Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	23591000	USD
CY2020Q3	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	3080000	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	31527000	USD
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	18101000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Noncontrolling Interest OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest	415000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Noncontrolling Interest OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest	317000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Noncontrolling Interest OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest	229000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Noncontrolling Interest OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest	-2664000	USD
CY2021Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	398209000	USD
CY2020Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	23768000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	503936000	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	148602000	USD
CY2020Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4935795000	USD
	slg	Profit Loss Less Minority Interest In Net Income Loss Operating Partnerships ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships	103804000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	384000	USD
	us-gaap	Dividends Preferred Stock DividendsPreferredStock	7475000	USD
	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	467000	USD
	slg	Reallocationof Noncontrolling Interest In Operating Partnership Increase Decrease ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease	-32475000	USD
	slg	Deferred Compensation Plan And Stock Award Net DeferredCompensationPlanAndStockAwardNet	14319000	USD
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	198887000	USD
	slg	Consolidation Of Joint Venture Interest ConsolidationOfJointVentureInterest	305000	USD
	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	173000	USD
	us-gaap	Stock Issued During Period Value Stock Dividend StockIssuedDuringPeriodValueStockDividend	123529000	USD
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.820
	us-gaap	Dividends Common Stock DividendsCommonStock	125836000	USD
CY2021Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4813757000	USD
CY2021Q3	slg	Profit Loss Less Minority Interest In Net Income Loss Operating Partnerships ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships	391028000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	6266000	USD
CY2021Q3	us-gaap	Dividends Preferred Stock DividendsPreferredStock	3738000	USD
CY2021Q3	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	146000	USD
CY2021Q3	slg	Reallocationof Noncontrolling Interest In Operating Partnership Increase Decrease ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease	15230000	USD
CY2021Q3	slg	Deferred Compensation Plan And Stock Award Net DeferredCompensationPlanAndStockAwardNet	7932000	USD
CY2021Q3	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	77957000	USD
CY2021Q3	slg	Consolidation Of Joint Venture Interest ConsolidationOfJointVentureInterest	5000	USD
CY2021Q3	us-gaap	Noncontrolling Interest Decrease From Deconsolidation NoncontrollingInterestDecreaseFromDeconsolidation	4476000	USD
CY2021Q3	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5230000	USD
CY2021Q3	us-gaap	Stock Issued During Period Value Stock Dividend StockIssuedDuringPeriodValueStockDividend	0	USD
CY2021Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.910
CY2021Q3	us-gaap	Dividends Common Stock DividendsCommonStock	60748000	USD
CY2021Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5082215000	USD
CY2019Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5517198000	USD
	slg	Profit Loss Less Minority Interest In Net Income Loss Operating Partnerships ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships	179450000	USD
	us-gaap	Minority Interest Decrease From Redemptions MinorityInterestDecreaseFromRedemptions	1536000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-53886000	USD
	us-gaap	Dividends Preferred Stock DividendsPreferredStock	7475000	USD
	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	364000	USD
	us-gaap	Stock Issued During Period Value Conversion Of Units StockIssuedDuringPeriodValueConversionOfUnits	8744000	USD
	slg	Reallocationof Noncontrolling Interest In Operating Partnership Increase Decrease ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease	31144000	USD
	slg	Deferred Compensation Plan And Stock Award Net DeferredCompensationPlanAndStockAwardNet	13493000	USD
	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	360868000	USD
	slg	Consolidation Of Joint Venture Interest ConsolidationOfJointVentureInterest	8186000	USD
	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	596000	USD
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.214
	us-gaap	Dividends Common Stock DividendsCommonStock	89272000	USD
CY2020Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5205762000	USD
CY2020Q3	slg	Profit Loss Less Minority Interest In Net Income Loss Operating Partnerships ProfitLossLessMinorityInterestInNetIncomeLossOperatingPartnerships	18011000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	6171000	USD
CY2020Q3	us-gaap	Dividends Preferred Stock DividendsPreferredStock	3738000	USD
CY2020Q3	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	202000	USD
CY2020Q3	us-gaap	Stock Issued During Period Value Conversion Of Units StockIssuedDuringPeriodValueConversionOfUnits	0	USD
CY2020Q3	slg	Reallocationof Noncontrolling Interest In Operating Partnership Increase Decrease ReallocationofNoncontrollingInterestInOperatingPartnershipIncreaseDecrease	4109000	USD
CY2020Q3	slg	Deferred Compensation Plan And Stock Award Net DeferredCompensationPlanAndStockAwardNet	7543000	USD
CY2020Q3	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	31127000	USD
CY2020Q3	slg	Consolidation Of Joint Venture Interest ConsolidationOfJointVentureInterest	4219000	USD
CY2020Q3	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	12530000	USD
CY2020Q3	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.911
CY2020Q3	us-gaap	Dividends Common Stock DividendsCommonStock	64617000	USD
CY2020Q3	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	5134005000	USD
	us-gaap	Profit Loss ProfitLoss	528813000	USD
	us-gaap	Profit Loss ProfitLoss	214418000	USD
	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	179039000	USD
	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	265048000	USD
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-31321000	USD
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	-15445000	USD
	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	719000	USD
	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	576000	USD
	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	-5438000	USD
	us-gaap	Equity Method Investment Realized Gain Loss On Disposal EquityMethodInvestmentRealizedGainLossOnDisposal	0	USD
	slg	Purchase Price Fair Value Adjustment Gain Loss PurchasePriceFairValueAdjustmentGainLoss	209527000	USD
	slg	Purchase Price Fair Value Adjustment Gain Loss PurchasePriceFairValueAdjustmentGainLoss	0	USD
	slg	Depreciable Real Estate Reserves And Impairment DepreciableRealEstateReservesAndImpairment	5696000	USD
	slg	Depreciable Real Estate Reserves And Impairment DepreciableRealEstateReservesAndImpairment	6627000	USD
	us-gaap	Gains Losses On Sales Of Investment Real Estate GainsLossesOnSalesOfInvestmentRealEstate	285338000	USD
	us-gaap	Gains Losses On Sales Of Investment Real Estate GainsLossesOnSalesOfInvestmentRealEstate	163624000	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	0	USD
	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	27018000	USD
	us-gaap	Straight Line Rent StraightLineRent	6963000	USD
	us-gaap	Straight Line Rent StraightLineRent	3459000	USD
	slg	Non Cash Lease Expense NonCashLeaseExpense	11670000	USD
	slg	Non Cash Lease Expense NonCashLeaseExpense	9735000	USD
	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-27868000	USD
	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-14874000	USD
	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	11827000	USD
	us-gaap	Increase Decrease In Accounts Receivable IncreaseDecreaseInAccountsReceivable	43069000	USD
	us-gaap	Increase Decrease In Due From Related Parties Current IncreaseDecreaseInDueFromRelatedPartiesCurrent	4626000	USD
	us-gaap	Increase Decrease In Due From Related Parties Current IncreaseDecreaseInDueFromRelatedPartiesCurrent	-4195000	USD
	us-gaap	Increase Decrease In Deferred Leasing Fees IncreaseDecreaseInDeferredLeasingFees	1267000	USD
	us-gaap	Increase Decrease In Deferred Leasing Fees IncreaseDecreaseInDeferredLeasingFees	12472000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	118000	USD
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	55301000	USD
	slg	Increase Decrease In Accrued Liabilities And Other IncreaseDecreaseInAccruedLiabilitiesAndOther	-54009000	USD
	slg	Increase Decrease In Accrued Liabilities And Other IncreaseDecreaseInAccruedLiabilitiesAndOther	43256000	USD
	us-gaap	Increase Decrease In Deferred Liabilities IncreaseDecreaseInDeferredLiabilities	7412000	USD
	us-gaap	Increase Decrease In Deferred Liabilities IncreaseDecreaseInDeferredLiabilities	13206000	USD
	slg	Increase Decrease In Operating Lease Liability IncreaseDecreaseInOperatingLeaseLiability	-33289000	USD
	slg	Increase Decrease In Operating Lease Liability IncreaseDecreaseInOperatingLeaseLiability	-8530000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	191012000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	327943000	USD
	us-gaap	Payments To Acquire Commercial Real Estate PaymentsToAcquireCommercialRealEstate	152791000	USD
	us-gaap	Payments To Acquire Commercial Real Estate PaymentsToAcquireCommercialRealEstate	86846000	USD
	slg	Payments To Acquire Land Buildings And Improvements PaymentsToAcquireLandBuildingsAndImprovements	208380000	USD
	slg	Payments To Acquire Land Buildings And Improvements PaymentsToAcquireLandBuildingsAndImprovements	281651000	USD
	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	76471000	USD
	us-gaap	Payments To Acquire Equity Method Investments PaymentsToAcquireEquityMethodInvestments	39724000	USD
	slg	Proceeds From Equity Method Investment Dividends Or Distributions ProceedsFromEquityMethodInvestmentDividendsOrDistributions	749997000	USD
	slg	Proceeds From Equity Method Investment Dividends Or Distributions ProceedsFromEquityMethodInvestmentDividendsOrDistributions	104300000	USD
	us-gaap	Proceeds From Real Estate And Real Estate Joint Ventures ProceedsFromRealEstateAndRealEstateJointVentures	541268000	USD
	us-gaap	Proceeds From Real Estate And Real Estate Joint Ventures ProceedsFromRealEstateAndRealEstateJointVentures	333037000	USD
	slg	Proceeds From Consolidation Of Real Estate Investment ProceedsFromConsolidationOfRealEstateInvestment	9475000	USD
	slg	Proceeds From Consolidation Of Real Estate Investment ProceedsFromConsolidationOfRealEstateInvestment	0	USD
	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	4528000	USD
	us-gaap	Proceeds From Sale And Maturity Of Marketable Securities ProceedsFromSaleAndMaturityOfMarketableSecurities	0	USD
	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	10000000	USD
	us-gaap	Payments To Acquire Marketable Securities PaymentsToAcquireMarketableSecurities	0	USD
	slg	Payments For Proceeds From Other Investments PaymentsForProceedsFromOtherInvestments	-2401000	USD
	slg	Payments For Proceeds From Other Investments PaymentsForProceedsFromOtherInvestments	3921000	USD
	slg	Origination Of Debt And Preferred Equity Investments OriginationOfDebtAndPreferredEquityInvestments	83924000	USD
	slg	Origination Of Debt And Preferred Equity Investments OriginationOfDebtAndPreferredEquityInvestments	353797000	USD
	slg	Repayments Or Redemption Of Debt And Preferred Equity Investments RepaymentsOrRedemptionOfDebtAndPreferredEquityInvestments	110774000	USD
	slg	Repayments Or Redemption Of Debt And Preferred Equity Investments RepaymentsOrRedemptionOfDebtAndPreferredEquityInvestments	703625000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	886877000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	375023000	USD
	us-gaap	Proceeds From Issuance Of Secured Debt ProceedsFromIssuanceOfSecuredDebt	31219000	USD
	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	925000000	USD
	us-gaap	Proceeds From Other Debt ProceedsFromOtherDebt	1275000000	USD
	us-gaap	Proceeds From Issuance Of Secured Debt ProceedsFromIssuanceOfSecuredDebt	1128775000	USD
	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	372300000	USD
	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	710352000	USD
	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	1165000000	USD
	us-gaap	Repayments Of Other Debt RepaymentsOfOtherDebt	1575000000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	613000	USD
	us-gaap	Proceeds From Stock Options Exercised ProceedsFromStockOptionsExercised	566000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	280623000	USD
	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	381992000	USD
	us-gaap	Payments For Repurchase Of Redeemable Preferred Stock PaymentsForRepurchaseOfRedeemablePreferredStock	3631000	USD
	us-gaap	Payments For Repurchase Of Redeemable Preferred Stock PaymentsForRepurchaseOfRedeemablePreferredStock	82750000	USD
	slg	Payments For Repurchase Of Partnership Units PaymentsForRepurchaseOfPartnershipUnits	13930000	USD
	slg	Payments For Repurchase Of Partnership Units PaymentsForRepurchaseOfPartnershipUnits	18913000	USD
	slg	Distributions To Noncontrolling Interests Other Partnerships DistributionsToNoncontrollingInterestsOtherPartnerships	5403000	USD
	slg	Distributions To Noncontrolling Interests Other Partnerships DistributionsToNoncontrollingInterestsOtherPartnerships	13126000	USD
	slg	Proceeds From Noncontrolling Interests In Other Partnerships ProceedsFromNoncontrollingInterestsInOtherPartnerships	310000	USD
	slg	Proceeds From Noncontrolling Interests In Other Partnerships ProceedsFromNoncontrollingInterestsInOtherPartnerships	12404000	USD
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	0	USD
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	1536000	USD
	slg	Distribution To Noncontrolling Interest Operating Partnership DistributionToNoncontrollingInterestOperatingPartnership	11882000	USD
	slg	Distribution To Noncontrolling Interest Operating Partnership DistributionToNoncontrollingInterestOperatingPartnership	8857000	USD
	us-gaap	Payments Of Dividends PaymentsOfDividends	205131000	USD
	us-gaap	Payments Of Dividends PaymentsOfDividends	224147000	USD
	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	2989000	USD
	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	4752000	USD
	slg	Deferred Loan Costs And Capitalized Lease Obligation DeferredLoanCostsAndCapitalizedLeaseObligation	570000	USD
	slg	Deferred Loan Costs And Capitalized Lease Obligation DeferredLoanCostsAndCapitalizedLeaseObligation	34687000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	434000	USD
	us-gaap	Finance Lease Principal Payments FinanceLeasePrincipalPayments	580000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1104751000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-639947000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-26862000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	63019000	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
CY2021Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	345933000	USD
CY2020Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	304449000	USD
	us-gaap	Partners Capital Account Redemptions PartnersCapitalAccountRedemptions	0	USD
	us-gaap	Partners Capital Account Redemptions PartnersCapitalAccountRedemptions	8744000	USD
	slg	Redemption Of Units In Partnership For Joint Venture Sale RedemptionOfUnitsInPartnershipForJointVentureSale	27586000	USD
	slg	Redemption Of Units In Partnership For Joint Venture Sale RedemptionOfUnitsInPartnershipForJointVentureSale	0	USD
	slg	Exchange Of Preferred Equity Investment For Real Estate Or Equity In Joint Venture ExchangeOfPreferredEquityInvestmentForRealEstateOrEquityInJointVenture	0	USD
	slg	Exchange Of Preferred Equity Investment For Real Estate Or Equity In Joint Venture ExchangeOfPreferredEquityInvestmentForRealEstateOrEquityInJointVenture	119467000	USD
	us-gaap	Transfer Of Investments TransferOfInvestments	9468000	USD
	us-gaap	Transfer Of Investments TransferOfInvestments	104211000	USD
	slg	Assumption Of Mortgage Loan AssumptionOfMortgageLoan	60000000	USD
	slg	Assumption Of Mortgage Loan AssumptionOfMortgageLoan	0	USD
	slg	Issuance Of Special Dividend Stock Dividend IssuanceOfSpecialDividendStockDividend	121418000	USD
	slg	Issuance Of Special Dividend Stock Dividend IssuanceOfSpecialDividendStockDividend	0	USD
	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	16684000	USD
	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	11993000	USD
	slg	Operating Partnership Noncontrolling Interest Fair Value Adjustment OperatingPartnershipNoncontrollingInterestFairValueAdjustment	17245000	USD
	slg	Operating Partnership Noncontrolling Interest Fair Value Adjustment OperatingPartnershipNoncontrollingInterestFairValueAdjustment	35253000	USD
	slg	Consolidation Of Real Estate Investment ConsolidationOfRealEstateInvestment	119444000	USD
	slg	Consolidation Of Real Estate Investment ConsolidationOfRealEstateInvestment	0	USD
	slg	Deconsolidation Of Subsidiary DeconsolidationOfSubsidiary	66837000	USD
	slg	Deconsolidation Of Subsidiary DeconsolidationOfSubsidiary	0	USD
	slg	Deconsolidation Of Subsidiary Mortgage DeconsolidationOfSubsidiaryMortgage	510000000	USD
	slg	Deconsolidation Of Subsidiary Mortgage DeconsolidationOfSubsidiaryMortgage	5593000	USD
	slg	Reversal Of Assets Held For Sale ReversalOfAssetsHeldForSale	0	USD
	slg	Reversal Of Assets Held For Sale ReversalOfAssetsHeldForSale	391664000	USD
	slg	Extinguishment Of Debt In Connection With Property Dispositions ExtinguishmentOfDebtInConnectionWithPropertyDispositions	53548000	USD
	slg	Extinguishment Of Debt In Connection With Property Dispositions ExtinguishmentOfDebtInConnectionWithPropertyDispositions	0	USD
	slg	Mortgages Assumed In Connection With Sale Of Real Estate MortgagesAssumedInConnectionWithSaleOfRealEstate	0	USD
	slg	Mortgages Assumed In Connection With Sale Of Real Estate MortgagesAssumedInConnectionWithSaleOfRealEstate	250000000	USD
	slg	Seller Financed Purchases SellerFinancedPurchases	0	USD
	slg	Seller Financed Purchases SellerFinancedPurchases	100000000	USD
	slg	Debt And Preferred Equity Reserves DebtAndPreferredEquityReserves	8372000	USD
	slg	Debt And Preferred Equity Reserves DebtAndPreferredEquityReserves	4638000	USD
	slg	Removalof Fully Depreciated Real Estate Assets RemovalofFullyDepreciatedRealEstateAssets	7030000	USD
	slg	Removalof Fully Depreciated Real Estate Assets RemovalofFullyDepreciatedRealEstateAssets	7906000	USD
	slg	Increase Decreasein Noncontrolling Interestin Joint Ventures IncreaseDecreaseinNoncontrollingInterestinJointVentures	358000	USD
	slg	Increase Decreasein Noncontrolling Interestin Joint Ventures IncreaseDecreaseinNoncontrollingInterestinJointVentures	0	USD
	slg	Share Repurchases Payable ShareRepurchasesPayable	3779000	USD
	slg	Share Repurchases Payable ShareRepurchasesPayable	10003000	USD
	slg	Sale Of Interest In Partially Owned Entity SaleOfInterestInPartiallyOwnedEntity	4476000	USD
	slg	Sale Of Interest In Partially Owned Entity SaleOfInterestInPartiallyOwnedEntity	0	USD
	slg	Recognition Of Sales Type Leases And Related Lease Liabilities RecognitionOfSalesTypeLeasesAndRelatedLeaseLiabilities	0	USD
	slg	Recognition Of Sales Type Leases And Related Lease Liabilities RecognitionOfSalesTypeLeasesAndRelatedLeaseLiabilities	114974000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	115812000	USD
	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	57500000	USD
CY2021Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	257941000	USD
CY2020Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	221404000	USD
CY2021Q3	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	87992000	USD
CY2020Q3	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	83045000	USD
CY2021Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	345933000	USD
CY2020Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	304449000	USD
CY2021Q3	us-gaap	Net Income Loss Per Outstanding Limited Partnership Unit Basic Net Of Tax NetIncomeLossPerOutstandingLimitedPartnershipUnitBasicNetOfTax	5.77
CY2021Q3	slg	Numberof Real Estate Buildings NumberofRealEstateBuildings	61	building
CY2021Q3	us-gaap	Area Of Real Estate Property AreaOfRealEstateProperty	28035572	sqft
CY2021Q3	slg	Real Estate Weighted Average Occupancy RealEstateWeightedAverageOccupancy	0.921
CY2021Q3	slg	Mortgage Loanson Real Estate Commercialand Consumer Net Including Debt Investments Other MortgageLoansonRealEstateCommercialandConsumerNetIncludingDebtInvestmentsOther	1100000000	USD
CY2021Q3	slg	Debt Investments Other DebtInvestmentsOther	100000000	USD
	slg	Number Of Shares On Redemption Of One Unit Of Partnership Interest NumberOfSharesOnRedemptionOfOneUnitOfPartnershipInterest	1	shares
CY2021Q3	slg	Rental Revenue Increase Decrease Acquired Lease Amortization RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization	-300000	USD
	slg	Rental Revenue Increase Decrease Acquired Lease Amortization RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization	-4000000	USD
CY2020Q3	slg	Rental Revenue Increase Decrease Acquired Lease Amortization RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization	1600000	USD
	slg	Rental Revenue Increase Decrease Acquired Lease Amortization RentalRevenueIncreaseDecreaseAcquiredLeaseAmortization	4500000	USD
CY2021Q3	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	226709000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	215673000	USD
CY2021Q3	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	191758000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	190523000	USD
CY2021Q3	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	34951000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	25150000	USD
CY2021Q3	slg	Finite Lived Intangible Liabilities Gross FiniteLivedIntangibleLiabilitiesGross	225029000	USD
CY2020Q4	slg	Finite Lived Intangible Liabilities Gross FiniteLivedIntangibleLiabilitiesGross	241409000	USD
CY2021Q3	slg	Finite Lived Intangible Liabilities Accumulated Amortization FiniteLivedIntangibleLiabilitiesAccumulatedAmortization	218371000	USD
CY2020Q4	slg	Finite Lived Intangible Liabilities Accumulated Amortization FiniteLivedIntangibleLiabilitiesAccumulatedAmortization	230479000	USD
CY2021Q3	slg	Finite Lived Intangible Liabilities Net FiniteLivedIntangibleLiabilitiesNet	6658000	USD
CY2020Q4	slg	Finite Lived Intangible Liabilities Net FiniteLivedIntangibleLiabilitiesNet	10930000	USD
CY2021Q3	slg	Net Intangible Assets Transferredto Assets Heldfor Sale NetIntangibleAssetsTransferredtoAssetsHeldforSale	0	USD
CY2020Q4	slg	Net Intangible Assets Transferredto Assets Heldfor Sale NetIntangibleAssetsTransferredtoAssetsHeldforSale	0	USD
CY2021Q3	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
CY2021Q3	us-gaap	Marketable Securities Unrealized Gain Loss MarketableSecuritiesUnrealizedGainLoss	2000000	USD
	us-gaap	Marketable Securities Unrealized Gain Loss MarketableSecuritiesUnrealizedGainLoss	100000	USD
CY2021Q3	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	4500000	USD
	slg	Debt Securities Available For Sale Number Of Securities Sold DebtSecuritiesAvailableForSaleNumberOfSecuritiesSold	1	security
	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2020Q3	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2021Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	0	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1500000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	0	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2000000	USD
	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>
	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.
	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
	us-gaap	Mortgage Loans On Real Estate Amortization Of Premium MortgageLoansOnRealEstateAmortizationOfPremium	145196000	USD
CY2020	us-gaap	Mortgage Loans On Real Estate Amortization Of Premium MortgageLoansOnRealEstateAmortizationOfPremium	1048643000	USD
	slg	Sec Schedule1229 Real Estate Companies Investment In Mortgage Loans On Real Estate Loan Loss Reserve Period Increase Decrease SECSchedule1229RealEstateCompaniesInvestmentInMortgageLoansOnRealEstateLoanLossReservePeriodIncreaseDecrease	6583000	USD
CY2020	slg	Sec Schedule1229 Real Estate Companies Investment In Mortgage Loans On Real Estate Loan Loss Reserve Period Increase Decrease SECSchedule1229RealEstateCompaniesInvestmentInMortgageLoansOnRealEstateLoanLossReservePeriodIncreaseDecrease	-11463000	USD
CY2021Q3	us-gaap	Mortgage Loans On Real Estate MortgageLoansOnRealEstate	1052110000	USD
CY2020Q4	us-gaap	Mortgage Loans On Real Estate MortgageLoansOnRealEstate	1076542000	USD
CY2021Q3	us-gaap	Mortgage Loans On Real Estate Commercial And Consumer Net MortgageLoansOnRealEstateCommercialAndConsumerNet	1052110000	USD
CY2021Q3	slg	Mortgage Loanson Real Estate Senior Financing MortgageLoansonRealEstateSeniorFinancing	6599960000	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
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
CY2020	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	20693000	USD
	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	6583000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	37033000	USD
CY2021Q3	us-gaap	Allowance For Loan And Lease Losses Real Estate AllowanceForLoanAndLeaseLossesRealEstate	6630000	USD
CY2020Q4	us-gaap	Allowance For Loan And Lease Losses Real Estate AllowanceForLoanAndLeaseLossesRealEstate	13213000	USD
CY2021Q3	slg	Financing Receivable Nonaccrual No Allowance Number FinancingReceivableNonaccrualNoAllowanceNumber	1	loan
CY2021Q3	us-gaap	Financing Receivable Nonaccrual No Allowance FinancingReceivableNonaccrualNoAllowance	225400000	USD
CY2021Q3	slg	Number Of Investments Nonperforming NumberOfInvestmentsNonperforming	1	investment
CY2020Q4	slg	Number Of Investments Nonperforming NumberOfInvestmentsNonperforming	1	investment
CY2021Q3	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	27700000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Nonaccrual Status FinancingReceivableRecordedInvestmentNonaccrualStatus	27700000	USD
CY2021Q3	us-gaap	Notes Receivable Gross NotesReceivableGross	1052110000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	1076542000	USD
CY2021Q3	us-gaap	Financing Receivable Originated In Current Fiscal Year FinancingReceivableOriginatedInCurrentFiscalYear	64515000	USD
CY2021Q3	us-gaap	Financing Receivable Originated In Fiscal Year Before Latest Fiscal Year FinancingReceivableOriginatedInFiscalYearBeforeLatestFiscalYear	276930000	USD
CY2021Q3	us-gaap	Financing Receivable Originated Two Years Before Latest Fiscal Year FinancingReceivableOriginatedTwoYearsBeforeLatestFiscalYear	310326000	USD
CY2021Q3	us-gaap	Financing Receivable Originated Three Years Before Latest Fiscal Year FinancingReceivableOriginatedThreeYearsBeforeLatestFiscalYear	400339000	USD
CY2021Q3	us-gaap	Notes Receivable Gross NotesReceivableGross	1052110000	USD
	slg	Financing Receivable Portfolio Segments Number FinancingReceivablePortfolioSegmentsNumber	1	segment
CY2021Q1	slg	Financing Receivable Portfolio Segments Number FinancingReceivablePortfolioSegmentsNumber	1	segment
CY2021Q3	slg	Financing Receivable Recorded In Other Assets FinancingReceivableRecordedInOtherAssets	50300000	USD
CY2020Q4	slg	Financing Receivable Recorded In Other Assets FinancingReceivableRecordedInOtherAssets	66200000	USD
CY2021Q3	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
CY2020Q3	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	0	USD
	us-gaap	Provision For Loan Losses Expensed ProvisionForLoanLossesExpensed	6300000	USD
	srt	Mortgage Loans On Real Estate Interest Rate MortgageLoansOnRealEstateInterestRate	0.0653
CY2021Q3	slg	Variable Interest Entity Not Primary Beneficiary Investment VariableInterestEntityNotPrimaryBeneficiaryInvestment	87400000	USD
CY2020Q4	slg	Variable Interest Entity Not Primary Beneficiary Investment VariableInterestEntityNotPrimaryBeneficiaryInvestment	134000000	USD
CY2020Q4	us-gaap	Equity Method Investments EquityMethodInvestments	3823322000	USD
CY2021Q3	us-gaap	Equity Method Investment Difference Between Carrying Amount And Underlying Equity EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity	429200000	USD
CY2021Q3	us-gaap	Deferred Costs Leasing Gross DeferredCostsLeasingGross	401826000	USD
CY2020Q4	us-gaap	Deferred Costs Leasing Gross DeferredCostsLeasingGross	447002000	USD
CY2021Q3	slg	Accumulated Amortization Of Deferred Costs AccumulatedAmortizationOfDeferredCosts	277189000	USD
CY2020Q4	slg	Accumulated Amortization Of Deferred Costs AccumulatedAmortizationOfDeferredCosts	269834000	USD
CY2021Q3	us-gaap	Deferred Costs Current And Noncurrent DeferredCostsCurrentAndNoncurrent	124637000	USD
CY2020Q4	us-gaap	Deferred Costs Current And Noncurrent DeferredCostsCurrentAndNoncurrent	177168000	USD
CY2021Q3	slg	Secured Debt Bearing Fixed Interest Amount SecuredDebtBearingFixedInterestAmount	1076153000	USD
CY2020Q4	slg	Secured Debt Bearing Fixed Interest Amount SecuredDebtBearingFixedInterestAmount	1083683000	USD
CY2021Q3	slg	Secured Debt Bearing Variable Interest Amount SecuredDebtBearingVariableInterestAmount	352581000	USD
CY2020Q4	slg	Secured Debt Bearing Variable Interest Amount SecuredDebtBearingVariableInterestAmount	917677000	USD
CY2021Q3	slg	Secured Debt Gross SecuredDebtGross	1428734000	USD
CY2020Q4	slg	Secured Debt Gross SecuredDebtGross	2001360000	USD
CY2021Q3	slg	Secured Debt Deferred Finance Costs Net SecuredDebtDeferredFinanceCostsNet	6447000	USD
CY2020Q4	slg	Secured Debt Deferred Finance Costs Net SecuredDebtDeferredFinanceCostsNet	21388000	USD
CY2021Q3	us-gaap	Secured Debt SecuredDebt	1422287000	USD
CY2020Q4	us-gaap	Secured Debt SecuredDebt	1979972000	USD
CY2021Q3	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	2100000000	USD
CY2020Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	2500000000	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal Remainder Of Fiscal Year LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear	192443000	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	1059420000	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	1576583000	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	538018000	USD
CY2021Q3	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	100812000	USD
CY2021Q3	slg	Long Term Debt Maturity After Year Four LongTermDebtMaturityAfterYearFour	681458000	USD
CY2021Q3	slg	Long Term Debt Maturities Repayments Of Principal LongTermDebtMaturitiesRepaymentsOfPrincipal	4148734000	USD
CY2021Q3	us-gaap	Interest Expense InterestExpense	34054000	USD
CY2020Q3	us-gaap	Interest Expense InterestExpense	42595000	USD
	us-gaap	Interest Expense InterestExpense	112423000	USD
	us-gaap	Interest Expense InterestExpense	144345000	USD
CY2021Q3	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	1229000	USD
CY2020Q3	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	2198000	USD
	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	4215000	USD
	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	6010000	USD
CY2021Q3	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	20141000	USD
CY2020Q3	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	20677000	USD
	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	58395000	USD
	us-gaap	Interest Costs Incurred Capitalized InterestCostsIncurredCapitalized	57528000	USD
CY2021Q3	us-gaap	Interest Income Operating InterestIncomeOperating	335000	USD
CY2020Q3	us-gaap	Interest Income Operating InterestIncomeOperating	580000	USD
	us-gaap	Interest Income Operating InterestIncomeOperating	1088000	USD
	us-gaap	Interest Income Operating InterestIncomeOperating	1727000	USD
CY2021Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-14807000	USD
CY2020Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-23536000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-57155000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-91100000	USD
CY2020Q4	us-gaap	Due From Joint Ventures DueFromJointVentures	27006000	USD
CY2021Q3	us-gaap	Due From Other Related Parties DueFromOtherRelatedParties	8778000	USD
CY2020Q4	us-gaap	Due From Other Related Parties DueFromOtherRelatedParties	7651000	USD
CY2021Q3	us-gaap	Due From Joint Ventures DueFromJointVentures	26896000	USD
CY2021Q3	us-gaap	Due From Related Parties DueFromRelatedParties	35674000	USD
CY2020Q4	us-gaap	Due From Related Parties DueFromRelatedParties	34657000	USD
CY2021Q3	slg	Total Shares Authorized TotalSharesAuthorized	260000000	shares
CY2021Q3	slg	Total Par Or Stated Value Per Share TotalParOrStatedValuePerShare	0.01
CY2021Q3	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	160000000	shares
CY2021Q3	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2021Q3	us-gaap	Excess Stock Shares Authorized ExcessStockSharesAuthorized	75000000	shares
CY2021Q3	slg	Excess Stock Par Or Stated Value Per Share ExcessStockParOrStatedValuePerShare	0.01
CY2021Q3	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	25000000	shares
CY2021Q3	us-gaap	Preferred Stock Par Or Stated Value Per Share PreferredStockParOrStatedValuePerShare	0.01
CY2021Q3	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
	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	3797082	shares
CY2021Q3	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	0	shares
	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	72.89
CY2021Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	388205000	USD
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	13859000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	486073000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	185104000	USD
CY2021Q3	us-gaap	Distributed Earnings DistributedEarnings	363000	USD
CY2020Q3	us-gaap	Distributed Earnings DistributedEarnings	333000	USD
	us-gaap	Distributed Earnings DistributedEarnings	1090000	USD
	us-gaap	Distributed Earnings DistributedEarnings	777000	USD
CY2021Q3	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	1942000	USD
CY2020Q3	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	0	USD
	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	1736000	USD
	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Basic UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic	141000	USD
CY2021Q3	slg	Net Income Loss Available To Common Stockholders After Distributed And Undistributed Earnings Allocation Basic NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic	385900000	USD
CY2020Q3	slg	Net Income Loss Available To Common Stockholders After Distributed And Undistributed Earnings Allocation Basic NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic	13526000	USD
	slg	Net Income Loss Available To Common Stockholders After Distributed And Undistributed Earnings Allocation Basic NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic	483247000	USD
	slg	Net Income Loss Available To Common Stockholders After Distributed And Undistributed Earnings Allocation Basic NetIncomeLossAvailableToCommonStockholdersAfterDistributedAndUndistributedEarningsAllocationBasic	184186000	USD
CY2021Q3	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	-363000	USD
CY2020Q3	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	-333000	USD
	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	-1090000	USD
	us-gaap	Undistributed Earnings Loss Allocated To Participating Securities Diluted UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted	-777000	USD
CY2021Q3	slg	Distributed Earnings Diluted DistributedEarningsDiluted	-1942000	USD
CY2020Q3	slg	Distributed Earnings Diluted DistributedEarningsDiluted	0	USD
	slg	Distributed Earnings Diluted DistributedEarningsDiluted	-1736000	USD
	slg	Distributed Earnings Diluted DistributedEarningsDiluted	-141000	USD
CY2021Q3	us-gaap	Dilutive Securities Effect On Basic Earnings Per Share Other DilutiveSecuritiesEffectOnBasicEarningsPerShareOther	22683000	USD
CY2020Q3	us-gaap	Dilutive Securities Effect On Basic Earnings Per Share Other DilutiveSecuritiesEffectOnBasicEarningsPerShareOther	802000	USD
	us-gaap	Dilutive Securities Effect On Basic Earnings Per Share Other DilutiveSecuritiesEffectOnBasicEarningsPerShareOther	28489000	USD
	us-gaap	Dilutive Securities Effect On Basic Earnings Per Share Other DilutiveSecuritiesEffectOnBasicEarningsPerShareOther	10073000	USD
CY2021Q3	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	410888000	USD
CY2020Q3	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	14661000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	514562000	USD
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	195177000	USD
CY2021Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	66840000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	70943000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	68275000	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	73373000	shares
CY2021Q3	slg	Incremental Common Shares Attributable To Redemption Of Units To Common Shares IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares	3834000	shares
CY2020Q3	slg	Incremental Common Shares Attributable To Redemption Of Units To Common Shares IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares	4029000	shares
	slg	Incremental Common Shares Attributable To Redemption Of Units To Common Shares IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares	4024000	shares
	slg	Incremental Common Shares Attributable To Redemption Of Units To Common Shares IncrementalCommonSharesAttributableToRedemptionOfUnitsToCommonShares	4123000	shares
CY2021Q3	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	813000	shares
CY2020Q3	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	442000	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	684000	shares
	us-gaap	Incremental Common Shares Attributable To Share Based Payment Arrangements IncrementalCommonSharesAttributableToShareBasedPaymentArrangements	441000	shares
CY2020Q3	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	0	shares
	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	104000	shares
	us-gaap	Incremental Common Shares Attributable To Nonvested Shares With Forfeitable Dividends IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends	0	shares
CY2021Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	71487000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	75414000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	73087000	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	77937000	shares
CY2021Q3	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	969631	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1032243	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1728767	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1032243	shares
	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1728767	shares
CY2021Q3	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	500000	USD
	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	1600000	USD
CY2020Q3	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	600000	USD
	us-gaap	Employee Service Share Based Compensation Allocation Of Recognized Period Costs Capitalized Amount EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount	1700000	USD
	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	-12127000	USD
	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	-18777000	USD
CY2021Q3	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
CY2021Q3	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	24355000	USD
CY2021Q3	us-gaap	Derivative Fair Value Of Derivative Asset DerivativeFairValueOfDerivativeAsset	97000	USD
CY2020Q3	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	-517000	USD
CY2021Q3	us-gaap	Interest Rate Cash Flow Hedge Gain Loss Reclassified To Earnings Net InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet	7208000	USD
CY2020Q3	us-gaap	Interest Rate Cash Flow Hedge Gain Loss Reclassified To Earnings Net InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet	6616000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	-13336000	USD
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	-61183000	USD
	us-gaap	Interest Rate Cash Flow Hedge Gain Loss Reclassified To Earnings Net InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet	19901000	USD
	us-gaap	Interest Rate Cash Flow Hedge Gain Loss Reclassified To Earnings Net InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet	12957000	USD
CY2021Q3	us-gaap	Operating Lease Lease Income Lease Payments OperatingLeaseLeaseIncomeLeasePayments	142979000	USD
CY2020Q3	us-gaap	Operating Lease Lease Income Lease Payments OperatingLeaseLeaseIncomeLeasePayments	171866000	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
	slg	Accumulated Other Comprehensive Income Loss Gain Lossfrom Changesin Fair Value AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue	0	USD
	slg	Accumulated Other Comprehensive Income Loss Gain Lossfrom Changesin Fair Value AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue	0	USD
CY2020Q3	slg	Accumulated Other Comprehensive Income Loss Gain Lossfrom Changesin Fair Value AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue	0	USD
CY2021Q3	slg	Accumulated Other Comprehensive Income Loss Gain Lossfrom Changesin Fair Value AccumulatedOtherComprehensiveIncomeLossGainLossfromChangesinFairValue	0	USD
CY2021Q3	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	41900000	USD
CY2021Q3	us-gaap	Assets Needed For Immediate Settlement Aggregate Fair Value AssetsNeededForImmediateSettlementAggregateFairValue	42400000	USD
	us-gaap	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	16300000	USD
	slg	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months Into Equity In Net Income CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonthsIntoEquityInNetIncome	4100000	USD
CY2021Q3	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	-593000	USD
	us-gaap	Operating Lease Lease Income Lease Payments OperatingLeaseLeaseIncomeLeasePayments	473466000	USD
	us-gaap	Operating Lease Lease Income Lease Payments OperatingLeaseLeaseIncomeLeasePayments	538601000	USD
CY2021Q3	us-gaap	Operating Lease Variable Lease Income OperatingLeaseVariableLeaseIncome	12660000	USD
CY2020Q3	us-gaap	Operating Lease Variable Lease Income OperatingLeaseVariableLeaseIncome	21979000	USD
	us-gaap	Operating Lease Variable Lease Income OperatingLeaseVariableLeaseIncome	58634000	USD
	us-gaap	Operating Lease Variable Lease Income OperatingLeaseVariableLeaseIncome	70892000	USD
CY2021Q3	slg	Operating Lease Lease Income Fixed And Variable Lease Payments OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments	155639000	USD
CY2020Q3	slg	Operating Lease Lease Income Fixed And Variable Lease Payments OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments	193845000	USD
	slg	Operating Lease Lease Income Fixed And Variable Lease Payments OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments	532100000	USD
	slg	Operating Lease Lease Income Fixed And Variable Lease Payments OperatingLeaseLeaseIncomeFixedAndVariableLeasePayments	609493000	USD
CY2021Q3	us-gaap	Amortization Of Above And Below Market Leases AmortizationOfAboveAndBelowMarketLeases	-276000	USD
CY2020Q3	us-gaap	Amortization Of Above And Below Market Leases AmortizationOfAboveAndBelowMarketLeases	1670000	USD
	us-gaap	Amortization Of Above And Below Market Leases AmortizationOfAboveAndBelowMarketLeases	-4037000	USD
	us-gaap	Amortization Of Above And Below Market Leases AmortizationOfAboveAndBelowMarketLeases	4539000	USD
CY2021Q3	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	155363000	USD
CY2020Q3	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	195515000	USD
	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	528063000	USD
	us-gaap	Operating Lease Lease Income OperatingLeaseLeaseIncome	614032000	USD
CY2021Q3	us-gaap	Sublease Income SubleaseIncome	52000000	USD
	us-gaap	Sublease Income SubleaseIncome	175500000	USD
	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	6010000	USD
CY2020Q3	us-gaap	Sublease Income SubleaseIncome	59800000	USD
	us-gaap	Sublease Income SubleaseIncome	180200000	USD
CY2021Q3	us-gaap	Sales Type Lease Selling Profit Loss SalesTypeLeaseSellingProfitLoss	0	USD
CY2020Q3	us-gaap	Sales Type Lease Selling Profit Loss SalesTypeLeaseSellingProfitLoss	-5973000	USD
	us-gaap	Sales Type Lease Selling Profit Loss SalesTypeLeaseSellingProfitLoss	0	USD
	us-gaap	Sales Type Lease Selling Profit Loss SalesTypeLeaseSellingProfitLoss	-5973000	USD
CY2021Q3	us-gaap	Sales Type Lease Interest Income SalesTypeLeaseInterestIncome	1108000	USD
CY2020Q3	us-gaap	Sales Type Lease Interest Income SalesTypeLeaseInterestIncome	484000	USD
	us-gaap	Sales Type Lease Interest Income SalesTypeLeaseInterestIncome	3313000	USD
	us-gaap	Sales Type Lease Interest Income SalesTypeLeaseInterestIncome	484000	USD
CY2021Q3	slg	Sales Type Lease Gain Loss Recognized SalesTypeLeaseGainLossRecognized	1108000	USD
CY2020Q3	slg	Sales Type Lease Gain Loss Recognized SalesTypeLeaseGainLossRecognized	-5489000	USD
	slg	Sales Type Lease Gain Loss Recognized SalesTypeLeaseGainLossRecognized	3313000	USD
CY2021Q3	slg	Finance Lease Interest Expense Capitalized FinanceLeaseInterestExpenseCapitalized	0	USD
	slg	Sales Type Lease Gain Loss Recognized SalesTypeLeaseGainLossRecognized	-5489000	USD
	slg	Operating Leases Minimum Lease Term OperatingLeasesMinimumLeaseTerm	P1Y
CY2021Q3	us-gaap	Finance Lease Liability Payments Remainder Of Fiscal Year FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear	871000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Remainder Of Fiscal Year LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear	7324000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due Next Twelve Months FinanceLeaseLiabilityPaymentsDueNextTwelveMonths	3522000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	29386000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due Year Two FinanceLeaseLiabilityPaymentsDueYearTwo	3570000	USD
CY2021Q3	slg	Operating Lease Cost Before Capitalized Operating Lease Costs OperatingLeaseCostBeforeCapitalizedOperatingLeaseCosts	7567000	USD
CY2020Q3	slg	Operating Lease Cost Before Capitalized Operating Lease Costs OperatingLeaseCostBeforeCapitalizedOperatingLeaseCosts	7751000	USD
	slg	Operating Lease Cost Before Capitalized Operating Lease Costs OperatingLeaseCostBeforeCapitalizedOperatingLeaseCosts	22702000	USD
	slg	Operating Lease Cost Before Capitalized Operating Lease Costs OperatingLeaseCostBeforeCapitalizedOperatingLeaseCosts	24486000	USD
CY2021Q3	slg	Operating Lease Cost Capitalized OperatingLeaseCostCapitalized	1010000	USD
CY2020Q3	slg	Operating Lease Cost Capitalized OperatingLeaseCostCapitalized	778000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due After Year Five FinanceLeaseLiabilityPaymentsDueAfterYearFive	256692000	USD
	slg	Operating Lease Cost Capitalized OperatingLeaseCostCapitalized	2699000	USD
	slg	Operating Lease Cost Capitalized OperatingLeaseCostCapitalized	2315000	USD
CY2021Q3	us-gaap	Operating Lease Cost OperatingLeaseCost	6557000	USD
CY2020Q3	us-gaap	Operating Lease Cost OperatingLeaseCost	6973000	USD
	us-gaap	Operating Lease Cost OperatingLeaseCost	20003000	USD
	us-gaap	Operating Lease Cost OperatingLeaseCost	22171000	USD
CY2021Q3	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	1229000	USD
CY2020Q3	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	2198000	USD
	slg	Finance Lease Interest Expense Before Capitalized Interest FinanceLeaseInterestExpenseBeforeCapitalizedInterest	4215000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	30911000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	29502000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due Year Three FinanceLeaseLiabilityPaymentsDueYearThree	3641000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	30545000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due Year Four FinanceLeaseLiabilityPaymentsDueYearFour	3810000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	30772000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due Year Five FinanceLeaseLiabilityPaymentsDueYearFive	3858000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	631532000	USD
CY2021Q3	us-gaap	Finance Lease Liability Payments Due FinanceLeaseLiabilityPaymentsDue	275964000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	789972000	USD
CY2021Q3	us-gaap	Finance Lease Liability Undiscounted Excess Amount FinanceLeaseLiabilityUndiscountedExcessAmount	150796000	USD
CY2021Q3	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	352615000	USD
CY2021Q3	us-gaap	Finance Lease Liability FinanceLeaseLiability	125168000	USD
CY2021Q3	us-gaap	Operating Lease Liability OperatingLeaseLiability	437357000	USD
CY2020Q3	slg	Finance Lease Interest Expense Capitalized FinanceLeaseInterestExpenseCapitalized	588000	USD
	slg	Finance Lease Interest Expense Capitalized FinanceLeaseInterestExpenseCapitalized	0	USD
	slg	Finance Lease Interest Expense Capitalized FinanceLeaseInterestExpenseCapitalized	2378000	USD
CY2021Q3	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	1229000	USD
CY2020Q3	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	1610000	USD
	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	4215000	USD
	us-gaap	Finance Lease Interest Expense FinanceLeaseInterestExpense	3632000	USD
CY2021Q3	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	180000	USD
CY2020Q3	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	304000	USD
	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	540000	USD
	us-gaap	Finance Lease Right Of Use Asset Amortization FinanceLeaseRightOfUseAssetAmortization	914000	USD
CY2021Q3	slg	Finance Lease Cost FinanceLeaseCost	1409000	USD
CY2020Q3	slg	Finance Lease Cost FinanceLeaseCost	1914000	USD
	slg	Finance Lease Cost FinanceLeaseCost	4755000	USD
	slg	Finance Lease Cost FinanceLeaseCost	4546000	USD
CY2021Q3	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0459
CY2021Q3	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P28Y
	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	2	segment
CY2021Q3	us-gaap	Revenues Revenues	205201000	USD
CY2020Q3	us-gaap	Revenues Revenues	249844000	USD
	us-gaap	Revenues Revenues	649410000	USD
	us-gaap	Revenues Revenues	817846000	USD
CY2021Q3	slg	Income Loss From Continuing Operations Before Realized Gain Loss On Disposal Of Equity Method Investment IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment	415534000	USD
CY2020Q3	slg	Income Loss From Continuing Operations Before Realized Gain Loss On Disposal Of Equity Method Investment IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment	20677000	USD
	slg	Income Loss From Continuing Operations Before Realized Gain Loss On Disposal Of Equity Method Investment IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment	528813000	USD
	slg	Income Loss From Continuing Operations Before Realized Gain Loss On Disposal Of Equity Method Investment IncomeLossFromContinuingOperationsBeforeRealizedGainLossOnDisposalOfEquityMethodInvestment	214418000	USD
CY2021Q3	us-gaap	Assets Assets	10855859000	USD
CY2020Q4	us-gaap	Assets Assets	11707567000	USD
CY2021Q3	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	23500000	USD
	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	68400000	USD
CY2020Q3	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	23600000	USD
	us-gaap	Selling General And Administrative Expense SellingGeneralAndAdministrativeExpense	66700000	USD

Files In Submission

Name	View Source	Status
0001040971-21-000034-index-headers.html	Edgar Link	pending
0001040971-21-000034-index.html	Edgar Link	pending
0001040971-21-000034.txt	Edgar Link	pending
0001040971-21-000034-xbrl.zip	Edgar Link	pending
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Financial_Report.xlsx	Edgar Link	pending
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slg-20210930_htm.xml	Edgar Link	completed
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slg-20210930_pre.xml	Edgar Link	unprocessable

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$SLG
SL Green Realty Corp Stock $slg

2021 Q4 Form 10-Q Financial Statement

#000104097121000034 Filed on November 09, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SLG SL Green Realty Corp Stock $slg

2021 Q4 Form 10-Q Financial Statement

#000104097121000034 Filed on November 09, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$SLG
SL Green Realty Corp Stock $slg