220 Central Park South 220 CPS - Narrative (Details) ft² in Thousands, $ in Thousands	3 Months Ended		6 Months Ended		9 Months Ended
	Jun. 30, 2019 USD ($) ft² unit	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) ft² unit	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) ft² unit
Real Estate [Line Items]
Net gain on sale of real estate			$ 2,571,099	$ 0
Income tax expense	$ 26,914	$ 467	56,657	3,021
Repayments of construction loan for Moynihan Train Hall			$ 205,783	$ 0
220 Central Park South
Real Estate [Line Items]
Square footage of real estate property (in sqft) | ft²	397		397		397
Development costs	$ 1,400,000		$ 1,400,000		$ 1,400,000
Development costs expended	$ 1,300,000		$ 1,300,000		$ 1,300,000
Number of condominium units sold (unit) | unit	11		23		34
Cash proceeds from the sale of real estate	$ 265,250		$ 690,734		$ 905,510
Net gain on sale of real estate	111,713		269,612
Income tax expense	22,792		49,737
Repayments of construction loan for Moynihan Train Hall					901,117
Construction loan	$ 950,000		$ 950,000		$ 950,000