220 Central Park South 220 CPS (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended		33 Months Ended
	Jun. 30, 2021 USD ($) unit	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) unit	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) unit
Real Estate [Line Items]
Income tax expense	$ 2,841	$ 1,837	$ 4,825	$ 14,650
220 Central Park South
Real Estate [Line Items]
Number of condominium units sold (unit) | unit	3		3		103
Cash proceeds from the sale of real estate	$ 72,216		$ 72,216		$ 2,941,708
Net gain on sale of real estate	25,272		25,272		$ 1,092,209
Income tax expense	$ 3,064		$ 3,064