Deferred Costs, Acquired Lease Intangibles and Goodwill - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Deferred Costs [Line Items]
Net deferred financing costs	$ 11,846		$ 11,846		$ 12,910
Amortization of deferred leasing costs	5,700	$ 5,500	11,500	$ 11,400
Revenue related to amortization of acquired above- and below-market leases, net	900	4,600	5,100	9,900
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	7,000	$ 9,300	14,700	$ 19,600
Unsecured Revolving Credit Facility | Revolving Credit Facility | Deferred costs, net
Deferred Costs [Line Items]
Net deferred financing costs	$ 4,000		$ 4,000