Intangible Assets (Components of Intangible Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Accumulated amortization	$ 85,341	$ 53,483
Goodwill	1,674	1,674	$ 3,626	$ 3,647
Total intangible assets	225,860	245,529
In-place Leases
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	170,234	185,251
Accumulated amortization	74,308	46,899
Above-market Tenant Leases
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	35,746	40,260
Accumulated amortization	10,826	6,515
Below-market Ground Lease
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	18,206	18,344
Accumulated amortization	$ 207	$ 69