XML 121 R106.htm IDEA: XBRL DOCUMENT v3.25.2

Financial Instruments: Derivatives and Hedging - Schedule of Notional and Fair Value of Derivative Financial Instruments and Foreign Currency Hedges (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Financial Instruments: Derivatives and Hedging
Fair Value	$ 11,848	$ 31,860
Interest Rate Contract
Financial Instruments: Derivatives and Hedging
Fair Value	(5,894)
July 2025
Financial Instruments: Derivatives and Hedging
Notional Value	$ 68,678
Strike Rate	4.00%
Fair Value	$ (5)
January 2026
Financial Instruments: Derivatives and Hedging
Notional Value	$ 150,000
Strike Rate	2.621%
Fair Value	$ 1,122
January 2026
Financial Instruments: Derivatives and Hedging
Notional Value	$ 200,000
Strike Rate	2.662%
Fair Value	$ 1,454
June 2026
Financial Instruments: Derivatives and Hedging
Notional Value	$ 72,314
Strike Rate	4.00%
Fair Value	$ (109)
December 2026
Financial Instruments: Derivatives and Hedging
Notional Value	$ 125,000
Strike Rate	3.667%
Fair Value	$ (174)
December 2026
Financial Instruments: Derivatives and Hedging
Notional Value	$ 125,000
Strike Rate	3.67%
Fair Value	$ (183)
February 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 100,000
Strike Rate	2.903%
Fair Value	$ 987
February 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 100,000
Strike Rate	2.733%
Fair Value	$ 1,252
February 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 50,000
Strike Rate	2.463%
Fair Value	$ 836
February 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 200,000
Strike Rate	2.591%
Fair Value	$ 2,947
May 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 300,000
Strike Rate	2.866%
Fair Value	$ 3,249
May 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 150,000
Strike Rate	3.524%
Fair Value	$ (158)
June 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 370,000
Strike Rate	3.888%
Fair Value	$ (3,064)
June 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 68,678
Strike Rate	4.466%
Fair Value	$ (1,348)
November 2027
Financial Instruments: Derivatives and Hedging
Notional Value	$ 300,000
Strike Rate	4.487%
Fair Value	$ (7,376)
January 2028
Financial Instruments: Derivatives and Hedging
Notional Value	$ 100,000
Strike Rate	3.756%
Fair Value	$ (890)
February 2028
Financial Instruments: Derivatives and Hedging
Notional Value	$ 80,000
Strike Rate	4.174%
Fair Value	$ (1,528)
May 2028
Financial Instruments: Derivatives and Hedging
Notional Value	$ 204,963
Strike Rate	3.915%
Fair Value	$ (2,906)
Due from joint venture | Interest Rate Contract
Financial Instruments: Derivatives and Hedging
Fair Value	(18,082)
Due from joint venture | July 2025
Financial Instruments: Derivatives and Hedging
Notional Value	$ 291,000
Strike Rate	4.00%
Fair Value	$ 20
Due from joint venture | November 2025
Financial Instruments: Derivatives and Hedging
Notional Value	$ 642,991
Strike Rate	4.00%
Fair Value	$ 655
Due from joint venture | September 2028
Financial Instruments: Derivatives and Hedging
Notional Value	$ 268,750
Strike Rate	4.039%
Fair Value	$ (5,625)
Due from joint venture | September 2028
Financial Instruments: Derivatives and Hedging
Notional Value	$ 268,750
Strike Rate	4.058%
Fair Value	$ (5,780)
Due from joint venture | September 2028
Financial Instruments: Derivatives and Hedging
Notional Value	$ 537,500
Strike Rate	4.065%
Fair Value	$ (11,799)
Due from joint venture | June 2026
Financial Instruments: Derivatives and Hedging
Notional Value	$ 289,257
Strike Rate	4.00%
Fair Value	$ 442

X

- Definition

Nominal or face amount used to calculate payments on the derivative asset.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-1A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13(Column A)(Footnote 3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5C
-Subparagraph (SX 210.12-13C(Column E))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5C

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5A
-Subparagraph (SX 210.12-13A(Column D))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5B
-Subparagraph (SX 210.12-13B(Column B))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-5B

+ Details

Name:	us-gaap_DerivativeAssetNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-7A

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-22

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-21

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-20

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-15

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483466/210-20-50-3

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-SubTopic 20
-Topic 860
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481326/860-20-50-4D

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 6A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480682/815-20-25-6A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateCapExpiringInJuly2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringJanuary2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateCapExpiringInJanuary20261Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateCapExpiringJune2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInDecember2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringDecemberIn20261Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInFebruary2027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInFebruary20272Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInFebruary20273Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInFebruary20274Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInMay2027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInMay20272Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInJune2027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInJune20272Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInNovember2027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInJanuary2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInFebruary2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInMay2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_CorporateJointVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateCapExpiringNovember2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringSeptember2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringSeptember20282Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringSeptember20283Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=slg_InterestRateSwapExpiringInJune2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: