Intangible Assets and Liabilities - Intangible Assets and Liabilities Summary (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Amortizable Intangible Assets
Finite-lived intangible assets, gross	$ 314,040	$ 310,534
Less: accumulated amortization	(126,012)	(120,395)
Finite-lived intangible assets, net	188,028	190,139
Goodwill	28,724	26,084
Total intangible assets, gross	342,764	336,618
Total intangible assets, net	216,752	216,223
Amortizable Intangible Liability
Finite-Lived Intangible Liabilities, Gross	(15,651)	(15,586)
Finite Lived Intangible Liabilities Accumulated Amortization	4,917	4,577
Finite Lived Intangible Liabilities Net	(10,734)	(11,009)
Below-market rent
Amortizable Intangible Liability
Finite-Lived Intangible Liabilities, Gross	(15,536)	(15,476)
Finite Lived Intangible Liabilities Accumulated Amortization	4,912	4,573
Finite Lived Intangible Liabilities Net	$ (10,624)	(10,903)
Below-market rent | Minimum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	4 years
Below-market rent | Maximum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	30 years
Above-market ground lease
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	81 years
Amortizable Intangible Liability
Finite-Lived Intangible Liabilities, Gross	$ (115)	(110)
Finite Lived Intangible Liabilities Accumulated Amortization	5	4
Finite Lived Intangible Liabilities Net	(110)	(106)
In-place lease
Amortizable Intangible Assets
Finite-lived intangible assets, gross	277,325	274,723
Less: accumulated amortization	(120,625)	(115,515)
Finite-lived intangible assets, net	$ 156,700	159,208
In-place lease | Minimum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	2 years
In-place lease | Maximum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	23 years
Below-market ground lease
Amortizable Intangible Assets
Finite-lived intangible assets, gross	$ 23,625	23,000
Less: accumulated amortization	(1,382)	(1,238)
Finite-lived intangible assets, net	$ 22,243	21,762
Below-market ground lease | Minimum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	15 years
Below-market ground lease | Maximum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	99 years
Above-market rent
Amortizable Intangible Assets
Finite-lived intangible assets, gross	$ 13,090	12,811
Less: accumulated amortization	(4,005)	(3,642)
Finite-lived intangible assets, net	$ 9,085	$ 9,169
Above-market rent | Minimum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	3 years
Above-market rent | Maximum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived intangible asset, useful life	30 years