Commitments and Contingencies - Major Customers and Other Concentrations (Details) - Customer concentration risk - Rental revenue - office_property	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Concentration Risk [Line Items]
Number of properties	6	6	6
Empire State Building
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	31.70%	32.80%	32.90%
One Grand Central Place
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	12.60%	12.40%	12.30%
111 West 33rd Street
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	11.30%	10.50%	9.90%
1400 Broadway
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	8.90%	8.00%	7.10%
250 West 57th Street
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	5.80%	5.70%	5.50%
First Stamford Place
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	5.20%	5.40%	5.40%
Tenant 1
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	4.60%	6.90%	6.80%
Tenant 2
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	3.30%	3.50%	3.20%
Tenant 3
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	2.80%		3.20%
Tenant 4
Concentration Risk [Line Items]
Concentration risk percentage (as a percent)	2.10%