Deferred Costs, Acquired Lease Intangibles and Goodwill - Deferred Costs, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Leasing costs	$ 171,865	$ 164,751
Total deferred costs, gross amount	443,883	469,530
Less: accumulated amortization	(206,210)	(215,102)
Total deferred costs, net, excluding net deferred financing costs	237,673	254,428
Acquired in-place lease value and deferred leasing costs
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets	218,810	237,364
Acquired above-market leases
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets	$ 53,208	$ 67,415