Mortgage Servicing Rights - Activity for Residential First-Lien Mortgage Servicing Rights (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of period	[1]			$ 139,293
Additions				36,834	$ 11,976
Changes in fair value due to:
Balance at End of Period	[1]	$ 168,462		168,462
Mortgage servicing rights
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of period		120,324	$ 64,971	139,293	64,824
Additions		32,463	11,807	51,217	14,666
Sales		0	0	(18,206)	0
Changes in fair value due to:
Changes in assumptions		19,168	(3,553)	5,132	(4,678)
Other changes		(3,493)	(2,000)	(8,974)	(3,587)
Balance at End of Period		$ 168,462	$ 71,225	$ 168,462	$ 71,225

[1] Our consolidated balance sheets include assets of consolidated variable interest entities (“VIEs”) that can only be used to settle obligations of these VIEs and liabilities of consolidated VIEs for which creditors do not have recourse to the primary beneficiary (Redwood Trust, Inc.). At June 30, 2015 and December 31, 2014, assets of consolidated VIEs totaled $1,622,636 and $1,900,208, respectively, and liabilities of consolidated VIEs totaled $1,263,249 and $1,546,490, respectively. See Note 4 for further discussion.