Deferred Costs, Acquired Lease Intangibles and Goodwill - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Deferred Costs [Line Items]
Net deferred financing costs	$ 12,095		$ 12,095		$ 12,910
Amortization of deferred leasing costs	6,100	$ 7,800	17,600	$ 19,200
Revenue related to amortization of acquired above- and below-market leases, net	1,200	4,800	6,300	14,700
Goodwill	491,479		491,479		$ 491,479
Observatory
Deferred Costs [Line Items]
Goodwill	227,500		227,500
Real Estate
Deferred Costs [Line Items]
Goodwill	264,000		264,000
Lease agreements
Deferred Costs [Line Items]
Amortization expense related to acquired lease intangibles	5,000	$ 9,800	19,700	$ 29,400
Unsecured Revolving Credit Facility | Revolving Credit Facility | Deferred costs, net
Deferred Costs [Line Items]
Net deferred financing costs	$ 5,000		$ 5,000