Intangible Assets and Liabilities - Intangible Assets and Liabilities Summary (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	$ 749,241	$ 740,965
Less: accumulated amortization	(259,056)	(245,900)
Finite-lived intangible assets, net	490,185	495,065
Indefinite-Lived Intangible Assets
Goodwill	304	304
Total intangible assets, gross	749,545	741,269
Total intangible assets, net	490,489	495,369
Finite-Lived Intangible Liabilities
Finite-lived intangible liabilities, gross	(83,904)	(83,404)
Less: accumulated amortization	23,350	22,182
Finite-lived intangible liabilities, net	(60,554)	(61,222)
Below-market rent
Finite-Lived Intangible Liabilities
Finite-lived intangible liabilities, gross	(82,759)	(82,259)
Less: accumulated amortization	23,285	22,121
Finite-lived intangible liabilities, net	$ (59,474)	(60,138)
Below-market rent | Minimum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	7 years
Below-market rent | Maximum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	53 years
Above-market ground lease
Finite-Lived Intangible Liabilities
Finite-lived intangible liabilities, gross	$ (1,145)	(1,145)
Less: accumulated amortization	65	61
Finite-lived intangible liabilities, net	$ (1,080)	(1,084)
Above-market ground lease | Minimum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	49 years
Above-market ground lease | Maximum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	88 years
In-place lease
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	$ 636,545	629,961
Less: accumulated amortization	(224,911)	(213,641)
Finite-lived intangible assets, net	$ 411,634	416,320
In-place lease | Minimum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	4 years
In-place lease | Maximum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	53 years
Above-market rent
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	$ 99,702	98,162
Less: accumulated amortization	(33,353)	(31,533)
Finite-lived intangible assets, net	$ 66,349	66,629
Above-market rent | Minimum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	7 years
Above-market rent | Maximum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	40 years
Below-market ground leases and other
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	$ 12,994	12,842
Less: accumulated amortization	(792)	(726)
Finite-lived intangible assets, net	$ 12,202	$ 12,116
Below-market ground leases and other | Minimum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	55 years
Below-market ground leases and other | Maximum
Intangible Assets Liabilities
Finite lived intangible asset/liability, useful life	94 years