Intangibles - Summary of Carrying Amount of Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Cost	$ 528,229	$ 452,384
Accumulated Amortization	(155,853)	(127,557)
Net	372,376	324,827
Liabilities
Below-market and Above-market ground leases, net	6,474	13,585
Lease liability, cost	63,697	0
Lease liability, accumulated amortization	(362)	0
Lease liability	63,335	0
Cost	78,152	20,619
Accumulated Amortization	(8,343)	(7,034)
Net	69,809	13,585
In-place leases
Assets
Cost	351,947	340,428
Accumulated Amortization	(137,246)	(111,500)
Net	214,701	228,928
Above-market leases
Assets
Cost	45,559	45,568
Accumulated Amortization	(16,799)	(13,621)
Net	28,760	31,947
Leasehold interest
Assets
Cost	712	712
Accumulated Amortization	(287)	(242)
Net	425	470
Below-market ground leases
Assets
Cost	0	65,676
Accumulated Amortization	0	(2,194)
Net	0	63,482
Right-of-use lease assets
Assets
Cost	130,011	0
Accumulated Amortization	(1,521)	0
Net	128,490	0
Below-market leases
Liabilities
Below-market and Above-market ground leases, cost	14,455	14,654
Below-market and Above-market ground leases, accumulated amortization	(7,981)	(6,768)
Below-market and Above-market ground leases, net	6,474	7,886
Above-market ground leases
Liabilities
Below-market and Above-market ground leases, cost	0	5,965
Below-market and Above-market ground leases, accumulated amortization	0	(266)
Below-market and Above-market ground leases, net	$ 0	$ 5,699