Summary of Changes to Stockholders' Equity (Detail) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Stockholders Equity Note [Line Items]
Balance at beginning of period	$ 1,074,811		$ 1,064,753
Other changes in equity, net	1,987		4,231
Unrealized gains on securities and derivatives, net	(41,491)		(31,718)
Common dividends declared	(20,236)		(40,360)	(39,908)
Net income attributable to Redwood Trust, Inc.	9,439	28,601	27,604	75,444
Balance at End of Period	$ 1,024,510		$ 1,024,510