Secured Financings - Summary of Key Terms of Revolving Repurchase Facilities (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2014
Line of Credit Facility [Line Items]
Facility mature date	Dec. 30, 2016
One-Month USD LIBOR [Member]
Line of Credit Facility [Line Items]
Percentage of revolving repurchase agreements	91.00%
Three-Month GBP LIBOR [Member]
Line of Credit Facility [Line Items]
Percentage of revolving repurchase agreements	7.00%
Floating Rate Indices [Member]
Line of Credit Facility [Line Items]
Percentage of revolving repurchase agreements	2.00%
Bank of America [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes two one-year extension options which may be exercised at our sole discretion.
MetLife [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes five one-year extension options which may be exercised at our sole discretion.