Segment Information - Assets Allocated by Segment (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Cash and cash equivalents	$ 436,401,000	$ 321,783,000	$ 337,432,000	$ 265,798,000
Restricted cash	40,013,000	40,017,000
Total Assets	781,098,000	761,912,000
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Total Assets	486,460,000	372,344,000
Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Assets	291,307,000	386,222,000
Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Assets	$ 3,331,000	$ 3,346,000