Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

+ Details

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- Definition

Represents the amount of gain (loss) incurred from the settlement of derivative instruments included in accumulated other comprehensive income (loss).

+ References

No definition available.

+ Details

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Namespace Prefix:	slg_
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Balance Type:	credit
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- Definition

Represents the estimated net amount of existing gains (losses) on cash flow hedges at the reporting date expected to be reclassified to equity in net income within the next 12 months.

+ References

No definition available.

+ Details

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Namespace Prefix:	slg_
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Balance Type:	credit
Period Type:	duration

- Definition

The aggregate fair value of assets needed to immediately settle the derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624258-113959

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- Definition

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7668309&loc=d3e80748-113994

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- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226000-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

+ Details

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- Definition

Fair value before effects of master netting arrangements, of a financial liability or 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.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

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Period Type:	instant

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Financial Instruments: Derivatives and Hedging (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financial Instruments: Derivatives and Hedging
Fair Value	$ 2,174,000
Fair Value	(14,728,000)	(1,329,000)
Derivative, Fair Value, Net	(12,554,000)
Loss from settlement of hedges included in accumulated other comprehensive loss	61,000	16,000	770,000
Fair value of derivatives in a net liability position	13,400,000
Aggregate termination value	13,400,000
Estimated current balance held in accumulated other comprehensive loss to be reclassified into earnings within the next 12 months	9,400,000
Share of joint venture of accumulated other comprehensive loss reclassified into equity in net income from unconsolidated joint ventures within the next 12 months	1,200,000
Amount of (Loss) or Gain Recognized in Other Comprehensive Loss (Effective Portion)	2,213,000	6,485,000	(10,549,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	8,430,000	7,005,000	12,676,000
Amount of Gain Recognized into Income (Ineffective Portion)	4,000	3,000	3,000
Level 2
Financial Instruments: Derivatives and Hedging
Fair Value	2,174,000
Fair Value	(14,728,000)	(1,329,000)
Joint venture
Financial Instruments: Derivatives and Hedging
Amount of (Loss) or Gain Recognized in Other Comprehensive Loss (Effective Portion)	2,916,000	6,553,000	(9,637,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	1,999,000	5,072,000	10,811,000
Amount of Gain Recognized into Income (Ineffective Portion)	0	0	0
Interest Rate Cap- Sold Expiring in May 2016
Financial Instruments: Derivatives and Hedging
Notional Value	504,000,000
Strike Rate (as a percent)	4.75%
Fair Value	4,000
Interest Rate Cap Expiring in May 2016
Financial Instruments: Derivatives and Hedging
Notional Value	504,000,000
Strike Rate (as a percent)	4.75%
Fair Value	(4,000)
Interest Rate Cap Expiring In May 2016
Financial Instruments: Derivatives and Hedging
Notional Value	500,000,000
Strike Rate (as a percent)	4.75%
Fair Value	4,000
Interest Rate Cap- Sold Expiring in May 2016
Financial Instruments: Derivatives and Hedging
Notional Value	500,000,000
Strike Rate (as a percent)	4.75%
Fair Value	(4,000)
Interest Rate Cap Expiring In May 2016
Financial Instruments: Derivatives and Hedging
Notional Value	446,000,000
Strike Rate (as a percent)	4.75%
Fair Value	3,000
Interest Rate Cap Expiring in November, 2015
Financial Instruments: Derivatives and Hedging
Notional Value	263,426,000
Strike Rate (as a percent)	6.00%
Fair Value	0
Interest Rate Cap Expiring in September 2015
Financial Instruments: Derivatives and Hedging
Notional Value	137,500,000
Strike Rate (as a percent)	4.00%
Fair Value	0
Interest Rate Swap
Financial Instruments: Derivatives and Hedging
Amount of (Loss) or Gain Recognized in Other Comprehensive Loss (Effective Portion)	(703,000)	(68,000)	(912,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	6,431,000	1,933,000	1,865,000
Amount of Gain Recognized into Income (Ineffective Portion)	4,000	3,000	3,000
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	200,000,000
Strike Rate (as a percent)	0.9375%
Fair Value	871,000
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	150,000,000
Strike Rate (as a percent)	0.94%
Fair Value	647,000
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	150,000,000
Strike Rate (as a percent)	0.94%
Fair Value	645,000
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	144,000,000
Strike Rate (as a percent)	2.236%
Fair Value	(4,757,000)
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	86,400,000
Strike Rate (as a percent)	1.9475%
Fair Value	(2,124,000)
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	72,000,000
Strike Rate (as a percent)	2.31%
Fair Value	(2,533,000)
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	72,000,000
Strike Rate (as a percent)	1.345%
Fair Value	(506,000)
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	72,000,000
Strike Rate (as a percent)	2.31%
Fair Value	(2,534,000)
Interest Rate Swap Expiring in December 2017
Financial Instruments: Derivatives and Hedging
Notional Value	57,600,000
Strike Rate (as a percent)	1.99%
Fair Value	(1,487,000)
Interest Rate Swap Expiring in June 2016
Financial Instruments: Derivatives and Hedging
Notional Value	30,000,000
Strike Rate (as a percent)	2.295%
Fair Value	(774,000)
Interest Rate Swap Expiring in February, 2015
Financial Instruments: Derivatives and Hedging
Notional Value	8,500,000
Strike Rate (as a percent)	0.74%
Fair Value	(5,000)
Interest Rate Swap Expiring in February, 2015 \| Level 2
Financial Instruments: Derivatives and Hedging
Loss from settlement of hedges included in accumulated other comprehensive loss			$ (700,000)