Lease Intangibles - Schedule of Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortizable Intangible Assets, Gross Carrying Amount	$ 210,607	$ 173,069
Amortizable Intangible Assets, Accumulated Amortization	(83,036)	(58,485)
Amortizable Intangible Assets, Net Carrying Amount	127,571	114,584
Amortizable Intangible Liabilities
Amortizable Intangible Liabilities, Gross Carrying Amount	(147,232)	(137,032)
Amortizable Intangible Liabilities, Accumulated Amortization	43,391	32,004
Amortizable Intangible Liabilities, Net Carrying Amount	(103,841)	(105,028)
Above-market Ground Lease, Gross	(671)	0
Above-market Ground Lease, Accumulated Amortization	34	0
Above-market Ground Lease, Net	(637)	0
Finite-Lived Intangible Liabilities, Gross	(147,903)	(137,032)
Finite-Lived Intangible Liabilities, Accumulated Amortization	43,425	32,004
Finite-Lived Intangible Liabilities, Net	(104,478)	(105,028)
Below market rents, acquired	$ 10,900
Below market rents acquired, weighted average useful life	12 years 1 month
Above-market ground lease, acquired	$ 700
Above-market ground lease acquired, weighted average useful life	11 years 6 months
In-place lease intangible assets
Finite-Lived Intangible Assets [Line Items]
Amortizable Intangible Assets, Gross Carrying Amount	$ 193,821	156,420
Amortizable Intangible Assets, Accumulated Amortization	(72,749)	(47,827)
Amortizable Intangible Assets, Net Carrying Amount	121,072	108,593
Intangible assets acquired	$ 41,600
Acquired intangible assets, weighted average useful life	4 years 1 month
Above-market rent
Finite-Lived Intangible Assets [Line Items]
Amortizable Intangible Assets, Gross Carrying Amount	$ 16,786	16,649
Amortizable Intangible Assets, Accumulated Amortization	(10,287)	(10,658)
Amortizable Intangible Assets, Net Carrying Amount	6,499	$ 5,991
Intangible assets acquired	$ 2,700
Acquired intangible assets, weighted average useful life	4 years 9 months