Securitization Activity Related to Unconsolidated Variable Interest Entity's Sponsored by Redwood (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended						6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2013 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-1	Jun. 30, 2012 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-1	Jun. 30, 2013 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-1 Trading Securities	Jun. 30, 2012 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-1 Trading Securities	Jun. 30, 2013 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-1 Available-for-sale Securities	Jun. 30, 2012 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-1 Available-for-sale Securities	Jun. 30, 2013 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-2	Jun. 30, 2012 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-2	Jun. 30, 2013 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-2 Trading Securities	Jun. 30, 2012 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-2 Trading Securities	Jun. 30, 2013 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-2 Available-for-sale Securities	Jun. 30, 2012 Variable Interest Entity, Not Primary Beneficiary SEMT 2012-2 Available-for-sale Securities
Variable Interest Entity [Line Items]
Principal balance of loans transferred			$ 1,802,058	$ 293,590					$ 4,042,710	$ 1,036,856
Securities retained, at fair value					40,642	5,610	92,367	17,267			91,850	26,786	207,095	56,717
Gains on sale				4,243						11,609
MSRs recognized	$ 16,000	$ 29,000	$ 16,148	$ 1,029					$ 28,614	$ 2,608