Secured Financings - Summary of Key Terms of Revolving Repurchase Facilities (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2014
Line of Credit Facility [Line Items]
Facility mature date	Dec. 30, 2016
MetLife [Member]
Line of Credit Facility [Line Items]
Maturity period	Includes five one-year extension options which may be exercised at our sole discretion.
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.