Consolidated Statement of Capital (Parenthetical) - $ / shares	1 Months Ended	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash distribution declared, per common share (in dollars per share)	$ 0.3122	$ 0.9108	$ 0.8748	$ 4.7908	$ 3.5352	$ 3.3834
SL Green Operating Partnership
Cash distribution declared, per common share (in dollars per share)				$ 4.7908	$ 3.5352	$ 3.3834

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration