Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 1,674	$ 1,674
Total intangible assets	255,613	145,883
In-place Leases
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	204,023	105,964
Accumulated amortization	162,263	125,130
Above-market Tenant Leases
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	32,332	20,453
Accumulated amortization	24,649	19,502
Below-market Ground Lease
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	17,584	17,792
Accumulated amortization	$ 828	$ 621