Lease Intangibles - Schedule of Intangible Assets and Liabilities Included in Other Assets and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortizable Intangible Assets, Gross Carrying Amount	$ 220,913	$ 210,607
Amortizable Intangible Assets, Accumulated Amortization	(108,664)	(83,036)
Amortizable Intangible Assets, Net Carrying Amount	112,249	127,571
Amortizable Intangible Liabilities
Amortizable Intangible Liabilities, Gross Carrying Amount	(149,149)	(147,232)
Amortizable Intangible Liabilities, Accumulated Amortization	51,965	43,391
Amortizable Intangible Liabilities, Net Carrying Amount	(97,184)	(103,841)
Above-market Ground Lease, Gross	(671)	(671)
Above-market Ground Lease, Accumulated Amortization	78	34
Above-market Ground Lease, Net	(593)	(637)
Finite-Lived Intangible Liabilities, Gross	(149,820)	(147,903)
Finite-Lived Intangible Liabilities, Accumulated Amortization	52,043	43,425
Finite-Lived Intangible Liabilities, Net	(97,777)	(104,478)
In-place lease intangible assets
Finite-Lived Intangible Assets [Line Items]
Amortizable Intangible Assets, Gross Carrying Amount	204,184	193,821
Amortizable Intangible Assets, Accumulated Amortization	(97,028)	(72,749)
Amortizable Intangible Assets, Net Carrying Amount	107,156	121,072
Amortizable Intangible Liabilities
Amortizable Intangible Liabilities, Net Carrying Amount	(92,091)
Above-market rent
Finite-Lived Intangible Assets [Line Items]
Amortizable Intangible Assets, Gross Carrying Amount	16,729	16,786
Amortizable Intangible Assets, Accumulated Amortization	(11,636)	(10,287)
Amortizable Intangible Assets, Net Carrying Amount	$ 5,093	$ 6,499