Fair Values of Real Estate Securities by Collateral Type and Entity (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Investment Holdings [Line Items]
Real Estate Securities	$ 1,037,601	$ 1,154,836
Redwood
Investment Holdings [Line Items]
Real Estate Securities	761,074	823,217
Redwood | Residential
Investment Holdings [Line Items]
Real Estate Securities	753,806	814,683
Redwood | Commercial
Investment Holdings [Line Items]
Real Estate Securities	5,865	7,496
Redwood | CDO
Investment Holdings [Line Items]
Real Estate Securities	1,403	1,038
Acacia
Investment Holdings [Line Items]
Real Estate Securities	276,527	308,363
Acacia | Residential
Investment Holdings [Line Items]
Real Estate Securities	213,755	248,494
Acacia | Commercial
Investment Holdings [Line Items]
Real Estate Securities	42,274	43,828
Acacia | CDO
Investment Holdings [Line Items]
Real Estate Securities	20,498	16,041
The Fund
Investment Holdings [Line Items]
Real Estate Securities		23,256
The Fund | Residential
Investment Holdings [Line Items]
Real Estate Securities		19,011
The Fund | CDO
Investment Holdings [Line Items]
Real Estate Securities		4,245
Residential
Investment Holdings [Line Items]
Real Estate Securities	967,561	1,082,188
Commercial
Investment Holdings [Line Items]
Real Estate Securities	48,139	51,324
CDO
Investment Holdings [Line Items]
Real Estate Securities	$ 21,901	$ 21,324