Loan Participations Sold - Summary of Statistics for Loan Participations Sold (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Participating Mortgage Loans [Line Items]
Interest paid	$ 127,429	$ 55,174	$ 12,702
Deferred financing costs	15,646	12,057
Loan Participations Sold [Member]
Participating Mortgage Loans [Line Items]
Interest expense	18,300	12,400
Interest paid	16,900	11,700
Deferred financing costs	$ 2,000	$ 3,400