Basis of Presentation Basis of Presentation - Narratives (Details) $ in Thousands	Mar. 31, 2018 USD ($) vie	Dec. 31, 2017 USD ($) vie
Variable Interest Entity
Variable interest entities, count	13	12
Variable interest entities consolidated, count	12	11
Variable interest entities unconsolidated, count	1	1
Equity investment in real estate | $	$ 20,179	$ 20,919
Equity method investments
Variable Interest Entity
Equity investment in real estate | $	$ 20,200	$ 20,900