Other Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Other Assets.
Deferred leasing costs	$ 30,232	$ 33,121
Deferred rent receivable	39,555	36,393
Internal-use software	17,248	14,440
Prepaid expense	8,396	4,390
Corporate furniture, fixtures and equipment	6,377	5,356
Deferred financing costs - revolving credit facility	1,119	1,604
Other	1,112	1,068
Total	$ 104,039	$ 96,372