Secured Financings - Summary of Loan Participations Sold (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2014
One-Month USD LIBOR [Member]
Participating Mortgage Loans [Line Items]
Percentage of sold participations indexed	40.00%
Three-Month GBP LIBOR [Member]
Participating Mortgage Loans [Line Items]
Percentage of sold participations indexed	60.00%