Deferred Costs, Acquired Lease Intangibles and Goodwill - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Deferred Costs [Line Items]
Amortization expense related to deferred leasing costs and acquired deferred leasing costs	$ 5,900
Amortization expense related to deferred leasing costs and acquired deferred leasing costs		$ 6,200
Rental revenue related to the amortization of below-market leases, net of above-market leases	908	2,354
Goodwill	491,479		$ 491,479
Observatory
Deferred Costs [Line Items]
Goodwill	227,500
Real estate
Deferred Costs [Line Items]
Goodwill	264,000
Lease agreements
Deferred Costs [Line Items]
Amortization expense related to acquired lease intangibles	$ 2,000	$ 3,200
Unsecured revolving credit facility | Unsecured revolving credit facility
Deferred Costs [Line Items]
Net deferred financing costs			$ 4,200