Lease Intangibles - Schedule of Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortizable Intangible Assets, Gross Carrying Amount	$ 203,512	$ 173,069
Amortizable Intangible Assets, Accumulated Amortization	(79,919)	(58,485)
Amortizable Intangible Assets, Net Carrying Amount	123,593	114,584
Amortizable Intangible Liabilities
Amortizable Intangible Liabilities, Gross Carrying Amount	(144,218)	(137,032)
Amortizable Intangible Liabilities, Accumulated Amortization	40,207	32,004
Amortizable Intangible Liabilities, Net Carrying Amount	(104,011)	(105,028)
Above-market Ground Lease, Gross	(671)	0
Above-market Ground Lease, Accumulated Amortization	19	0
Above-market Ground Lease, Net	(652)	0
Finite-Lived Intangible Liabilities, Gross	(144,889)	(137,032)
Finite-Lived Intangible Liabilities, Accumulated Amortization	40,226	32,004
Finite-Lived Intangible Liabilities, Net	(104,663)	(105,028)
Below market rents, acquired	$ 7,600
Below market rents acquired, weighted average useful life	11 years 6 months
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	$ 185,273	156,420
Amortizable Intangible Assets, Accumulated Amortization	(67,747)	(47,827)
Amortizable Intangible Assets, Net Carrying Amount	117,526	108,593
Intangible assets acquired	$ 29,600
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	$ 18,239	16,649
Amortizable Intangible Assets, Accumulated Amortization	(12,172)	(10,658)
Amortizable Intangible Assets, Net Carrying Amount	6,067	$ 5,991
Intangible assets acquired	$ 1,800
Acquired intangible assets, weighted average useful life	4 years 7 months