Summary of Unconsolidated Variable Interest Entity's Sponsored by Redwood (Detail) (Variable Interest Entity, Not Primary Beneficiary, USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
On-balance sheet assets, at fair value:
Maximum loss exposure	$ 503,709	[1]	$ 124,090	[1]
Principal balance of loans outstanding	6,414,120		1,736,331
Interest-only Securities
On-balance sheet assets, at fair value:
Securities	117,443		10,409
Subordinate Securities
On-balance sheet assets, at fair value:
Securities	$ 386,266		$ 113,681

[1] Maximum loss exposure from our involvement with unconsolidated VIEs pertains to the carrying value of our securities retained from these VIEs and represents estimated losses that would be incurred under severe, hypothetical circumstances, such as if the value of our interests and any associated collateral declines to zero. This does not include, for example, any potential exposure to representation and warranty claims associated with our initial transfer of loans into a securitization.