Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Other Assets.
Deferred rent receivable	$ 42,126	$ 43,162
Initial direct costs	23,875	24,651
Internal-use software	17,543	17,708
Prepaid expense	10,480	7,090
Corporate furniture, fixtures and equipment	4,720	5,006
Deferred financing costs - revolving credit facility	2,660	2,880
Other	2,037	1,793
Total	$ 103,441	$ 102,290