Intangibles - Summary of Carrying Amount of Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets
Cost	$ 402,608	$ 301,462
Accumulated Amortization	(87,255)	(63,177)
Net	315,353	238,285
Liability
Cost	19,706	11,642
Accumulated amortization	(4,026)	(2,389)
Net	15,680	9,253
In-place lease intangible
Assets
Cost	301,293	222,394
Accumulated Amortization	(75,354)	(55,605)
Net	225,939	166,789
Above market in-place lease intangible
Assets
Cost	51,967	35,478
Accumulated Amortization	(10,613)	(6,909)
Net	41,354	28,569
Leasehold interest
Assets
Cost	712	712
Accumulated Amortization	(168)	(124)
Net	544	588
Below market in-place ground lease
Assets
Cost	48,636	42,878
Accumulated Amortization	(1,120)	(539)
Net	47,516	42,339
Below market in-place lease intangible
Liability
Below market lease, cost	13,741	10,297
Below market lease, accumulated amortization	(3,933)	(2,345)
Below Market Lease, Net	9,808	7,952
Above market ground leases
Liability
Cost	5,965	1,345
Accumulated amortization	(93)	(44)
Net	$ 5,872	$ 1,301