Variable Interest Entities - Additional Information (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) Property Venture	Dec. 31, 2016 USD ($)
Variable Interest Entity [Line Items]
Number of industrial properties | Property	5
Number of joint venture | Venture	2
Total investment in mortgages and loans, net	$ 1,244,191	$ 1,280,285
Indebtedness	1,588,067	1,751,082
VIE
Variable Interest Entity [Line Items]
Total investment in mortgages and loans, net	1,199,111	1,184,588
Indebtedness	1,185,657	1,288,258
VIE | Consolidation Eliminations
Variable Interest Entity [Line Items]
Total investment in mortgages and loans, net	406,590	549,879
Indebtedness	$ 484,065	$ 510,244