XML 70 R55.htm IDEA: XBRL DOCUMENT
v3.20.2

Organization and Basis of Presentation - Subsequent Events (Details) - Subsequent Event - USD ($) $ in Millions | Nov. 04, 2020 | Oct. 31, 2020
--- | --- | ---
410 Tenth Avenue |  |
Subsequent Event [Line Items] |  |
Gross asset valuation |  | $ 952.5
Ownership Interest |  | 70.90%
Ownership percentage retained by investee |  | 5.00%
Third Quarter 2020 |  |
Subsequent Event [Line Items] |  |
Gross tenant billings collected, percent | 92.70% |
Third Quarter 2020 | Office |  |
Subsequent Event [Line Items] |  |
Gross tenant billings collected, percent | 96.90% |
Third Quarter 2020 | Retail |  |
Subsequent Event [Line Items] |  |
Gross tenant billings collected, percent | 70.20% |
October 2020 Period |  |
Subsequent Event [Line Items] |  |
Gross tenant billings collected, percent | 93.00% |
October 2020 Period | Office |  |
Subsequent Event [Line Items] |  |
Gross tenant billings collected, percent | 96.40% |
October 2020 Period | Retail |  |
Subsequent Event [Line Items] |  |
Gross tenant billings collected, percent | 72.60% |

X
- Definition Gross Tenant Billings Collected, Percent + References No definition available. + Details
Name: | slg_GrossTenantBillingsCollectedPercent
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ownership Percentage Retained By Investee + References No definition available. + Details
Name: | slg_OwnershipPercentageRetainedByInvestee
Namespace Prefix: | slg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation. + References No definition available. + Details
Name: | us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=slg_A410TenthAvenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | slg_LeasePaymentPeriodAxis=slg_ThirdQuarter2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | slg_LeasePaymentPeriodAxis=slg_October2020PeriodMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |