Intangibles - Amortization of Deferred Leasing Costs and Acquisition Related Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Intangibles
Depreciation and amortization expense related to amortization of lease-up intangibles	$ 67,350	$ 76,732	$ 84,487
Rental and related revenues related to amortization of net below market lease liabilities	5,253	2,030	3,877
Operating expense related to amortization of net below market ground lease intangibles	$ 636	$ 740	$ 664