Leases - Additional Information (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) item
Operating Leased Assets [Line Items]
Variable lease revenues	$ 14,600	$ 13,300
Operating lease, right-of-use asset	59,386		$ 60,006
Number of operating lease | item			9
Number of finance lease | item			4
Finance lease, right-of-use asset	102,050		$ 102,055
Reserves for credit losses	$ 2,500
565 Broadway | Core Portfolio
Operating Leased Assets [Line Items]
Operating lease, right-of-use asset			4,900
Finance lease, right-of-use asset			19,400
110 University Place
Operating Leased Assets [Line Items]
Operating lease, right-of-use asset			45,300
Operating lease liabilities			45,300
Capital Lease Liability
Operating Leased Assets [Line Items]
Finance lease liabilities			71,100
Ground, Office and Equipment Leases
Operating Leased Assets [Line Items]
Operating lease, right-of-use asset			82,600
Operating lease liabilities			76,600
Capital Leases Asset
Operating Leased Assets [Line Items]
Finance lease, right-of-use asset			77,000
Accounting Standards Update 2016-02
Operating Leased Assets [Line Items]
Operating lease, right-of-use asset			11,900
Operating lease liabilities			$ 12,800
Number of finance lease | item			3
Minimum
Operating Leased Assets [Line Items]
Operating lease term	1 month
Maximum
Operating Leased Assets [Line Items]
Operating lease term	60 years