XML 84 R69.htm IDEA: XBRL DOCUMENT
v3.21.2

Investments in Unconsolidated Joint Ventures - Additional Information (Details) $ in Thousands | 1 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
May 31, 2021 | Sep. 30, 2021 USD ($) ft² unit partner | Dec. 31, 2020 USD ($) | Jul. 31, 2021 ft²
General information on each joint venture |  |  |  |
Equity method investments | $ |  | $ 3,028,084 | $ 3,823,322 |
Net equity investment in VIEs in which the entity is not primary beneficiary | $ |  | $ 87,400 | $ 134,000 |
Unaudited Approximate Square Feet (sqft) |  | 28,035,572 |  |
One Madison Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership percentage deconsolidated |  |  | 50.50% |
Investment fair value adjustment | $ |  | $ 2,700 | $ 187,500 |
Worldwide Plaza |  |  |  |
General information on each joint venture |  |  |  |
Ownership percentage acquired | 1.20% |  |  |
Increase in ownership interest | 0.60% |  |  |
One Madison Avenue |  |  |  |
General information on each joint venture |  |  |  |
Investment in joint venture aggregate equity committed by partner | $ |  |  | $ 492,200 |
Investment in joint venture aggregate maximum ownership percentage |  |  | 49.50% |
Investment in joint venture, number of partners | partner |  | 2 |  |
Investment in joint venture, ownership percentage |  | 9.00% |  |
220 East 42nd Street | 220 East 42nd Street |  |  |  |
General information on each joint venture |  |  |  |
Ownership percentage deconsolidated |  |  |  | 51.00%
Investment fair value adjustment | $ |  | $ 206,800 |  |
220 East 42nd Street |  |  |  |
General information on each joint venture |  |  |  |
Unaudited Approximate Square Feet (sqft) |  |  |  | 1,135,000
Ownership interest disposed |  |  |  | 49.00%
21 East 66th Street | Three Retail and Two Residential Units |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 32.28% |  |
Number of stores | unit |  | 3 |  |
Number of residential units | unit |  | 1 |  |
21 East 66th Street | Three Residential Units |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 16.14% |  |
Number of residential units | unit |  | 2 |  |
Joint venture |  |  |  |
General information on each joint venture |  |  |  |
Equity method investments | $ |  | $ 3,028,084 |  |
Equity method investments with negative book value | $ |  | $ 100,200 |  |
Joint venture | 100 Park Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 49.90% |  |
Economic Interest (as a percent) |  | 49.90% |  |
Unaudited Approximate Square Feet (sqft) |  | 834,000 |  |
Joint venture | 717 Fifth Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 10.92% |  |
Economic Interest (as a percent) |  | 10.92% |  |
Unaudited Approximate Square Feet (sqft) |  | 119,500 |  |
Joint venture | 800 Third Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 60.52% |  |
Economic Interest (as a percent) |  | 60.52% |  |
Unaudited Approximate Square Feet (sqft) |  | 526,000 |  |
Joint venture | 919 Third Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 51.00% |  |
Economic Interest (as a percent) |  | 51.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 1,454,000 |  |
Joint venture | 11 West 34th Street |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 30.00% |  |
Economic Interest (as a percent) |  | 30.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 17,150 |  |
Joint venture | 280 Park Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 50.00% |  |
Economic Interest (as a percent) |  | 50.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 1,219,158 |  |
Joint venture | 1552-1560 Broadway |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 50.00% |  |
Economic Interest (as a percent) |  | 50.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 57,718 |  |
Joint venture | 10 East 53rd Street |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 55.00% |  |
Economic Interest (as a percent) |  | 55.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 354,300 |  |
Joint venture | 21 East 66th Street |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 32.28% |  |
Economic Interest (as a percent) |  | 32.28% |  |
Unaudited Approximate Square Feet (sqft) |  | 13,069 |  |
Joint venture | 650 Fifth Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 50.00% |  |
Economic Interest (as a percent) |  | 50.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 69,214 |  |
Joint venture | 121 Greene Street |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 50.00% |  |
Economic Interest (as a percent) |  | 50.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 7,131 |  |
Joint venture | Stonehenge Portfolio |  |  |  |
General information on each joint venture |  |  |  |
Unaudited Approximate Square Feet (sqft) |  | 1,439,016 |  |
Joint venture | 11 Madison Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 60.00% |  |
Economic Interest (as a percent) |  | 60.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 2,314,000 |  |
Joint venture | One Vanderbilt |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 71.01% |  |
Economic Interest (as a percent) |  | 71.01% |  |
Unaudited Approximate Square Feet (sqft) |  | 1,657,198 |  |
Joint venture | Worldwide Plaza |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 24.95% |  |
Economic Interest (as a percent) |  | 24.95% |  |
Unaudited Approximate Square Feet (sqft) |  | 2,048,725 |  |
Joint venture | 1515 Broadway |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 56.87% |  |
Economic Interest (as a percent) |  | 56.87% |  |
Unaudited Approximate Square Feet (sqft) |  | 1,750,000 |  |
Joint venture | 2 Herald Square |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 51.00% |  |
Economic Interest (as a percent) |  | 51.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 369,000 |  |
Joint venture | 115 Spring Street |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 51.00% |  |
Economic Interest (as a percent) |  | 51.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 5,218 |  |
Joint venture | 15 Beekman |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 20.00% |  |
Economic Interest (as a percent) |  | 20.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 221,884 |  |
Joint venture | 85 Fifth Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 36.30% |  |
Economic Interest (as a percent) |  | 36.30% |  |
Unaudited Approximate Square Feet (sqft) |  | 12,946 |  |
Joint venture | One Madison Avenue |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 50.50% |  |
Economic Interest (as a percent) |  | 50.50% |  |
Unaudited Approximate Square Feet (sqft) |  | 1,048,700 |  |
Joint venture | 220 East 42nd Street |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 51.00% |  |
Economic Interest (as a percent) |  | 51.00% |  |
Unaudited Approximate Square Feet (sqft) |  | 1,135,000 |  |
Joint venture | East 400 Street 57 |  |  |  |
General information on each joint venture |  |  |  |
Ownership interest |  | 41.00% |  |

X
- Definition Disposal Group, Including Discontinued Operation, Ownership Interest Disposed + References No definition available. + Details
Name: | slg_DisposalGroupIncludingDiscontinuedOperationOwnershipInterestDisposed
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage of economic interest in the investee accounted for under the equity method of accounting. + References No definition available. + Details
Name: | slg_EquityMethodInvestmentEconomicInterestPercentage
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Method Investment, Ownership Percentage, Deconsolidated + References No definition available. + Details
Name: | slg_EquityMethodInvestmentOwnershipPercentageDeconsolidated
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Method Investments, Ownership Percentage Acquired + References No definition available. + Details
Name: | slg_EquityMethodInvestmentsOwnershipPercentageAcquired
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity Method Investments, Ownership Percentage, Increase (Decrease) + References No definition available. + Details
Name: | slg_EquityMethodInvestmentsOwnershipPercentageIncreaseDecrease
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity Method Investments With Negative Book Value + References No definition available. + Details
Name: | slg_EquityMethodInvestmentsWithNegativeBookValue
Namespace Prefix: | slg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investment In Joint Venture Aggregate Equity Committed By Partner + References No definition available. + Details
Name: | slg_InvestmentInJointVentureAggregateEquityCommittedByPartner
Namespace Prefix: | slg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Investment In Joint Venture Aggregate Maximum Ownership Percentage + References No definition available. + Details
Name: | slg_InvestmentInJointVentureAggregateMaximumOwnershipPercentage
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Investment in Joint Venture, Number Of Partners In Joint Venture + References No definition available. + Details
Name: | slg_InvestmentInJointVentureNumberOfPartnersInJointVenture
Namespace Prefix: | slg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Investment in Joint Venture, Partners' Ownership Percentage + References No definition available. + Details
Name: | slg_InvestmentinJointVenturePartnersOwnershipPercentage
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number Of Residential Units + References No definition available. + Details
Name: | slg_NumberOfResidentialUnits
Namespace Prefix: | slg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the amount of equity investment in variable interest entities (VIEs) in which the entity is not a primary beneficiary. + References No definition available. + Details
Name: | slg_VariableInterestEntityNotPrimaryBeneficiaryInvestment
Namespace Prefix: | slg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Area of a real estate property. + References No definition available. + Details
Name: | us-gaap_AreaOfRealEstateProperty
Namespace Prefix: | us-gaap_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of addition (reduction) to the amount at which an asset could be incurred (settled) in a current transaction between willing parties. + References No definition available. + Details
Name: | us-gaap_AssetsFairValueAdjustment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 25 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8813-108599 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_EquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the number of stores. + References No definition available. + Details
Name: | us-gaap_NumberOfStores
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
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 No definition available. + Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=slg_OneMadisonAvenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_WorldwidePlazaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_OneMadisonAvenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_East220Street42Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=slg_East220Street42Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=slg_East220Street42Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | slg_RealEstateByLocationAxis=slg_East21Street66Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=slg_ThreeRetailandTwoResidentialUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=slg_ThreeResidentialUnitsMember
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: | srt_StatementGeographicalAxis=slg_ParkAvenue100Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_FifthAvenue717Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_ThirdAvenue800Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_ThirdAvenue919Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_West11Street34Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_ParkAvenue280Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_Broadway1552To1560Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_East53rdStreet10Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_East21Street66Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_A650FifthAvenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_GreeneStreet121Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_StonehengePropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_A11MadisonAveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_OneVanderbiltMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_Broadway1515Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_A2HeraldSquareMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_SpringStreet115Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_A15BeekmanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=slg_A85FifthAvenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=slg_East400Street57Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |