Cover Page - shares	9 Months Ended
	Sep. 30, 2019	Nov. 05, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	1-13759
Entity Registrant Name	REDWOOD TRUST INC
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	68-0329422
Entity Address Address Line	One Belvedere Place, Suite 300
Entity Address City Or Town	Mill Valley,
Entity Address, State or Province	CA
Entity Address Postal Zip Code	94941
City Area Code	415
Local Phone Number	389-7373
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity small business	false
Emerging growth company	false
Entity Shell Company	false
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	RWT
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		112,689,511
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000930236
Current Fiscal Year End Date	--12-31
Amendment Flag	false