Subsequent Events - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended		1 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013 Residential Loans	Jul. 31, 2013 Residential Loans Subsequent Event Investment	Aug. 05, 2013 Residential Loans Subsequent Event
Subsequent Events [Line Items]
Amount of loans planned to be purchased			$ 1,390,000,000
Residential mortgage loans closed and purchased					753,000,000
Principal balance of loans transferred	$ 1,800,000,000	$ 4,040,000,000		$ 7,000,000
Number of Sequoia securitization transactions				2