Equity - Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Per share data:
Net (loss) income attributable to Redwood	$ (581,847)	$ 169,183	$ 119,600
Less: Dividends and undistributed earnings allocated to participating securities	(1,990)	(4,797)	(3,754)
Net (loss) income allocated to common shareholders	$ (583,837)	$ 164,386	$ 115,846
Basic weighted average common shares outstanding (in shares)	113,935,605	101,120,744	78,724,912
Basic earnings per common share (in dollars per share)	$ (5.12)	$ 1.63	$ 1.47
Less: Dividends and undistributed earnings allocated to participating securities	$ (1,990)	$ (5,273)	$ (4,283)
Adjust for interest expense and gain on extinguishment of convertible notes for the period, net of tax	0	36,212	32,653
Net (loss) income allocated to common shareholders	$ (583,837)	$ 200,122	$ 147,970
Weighted average common shares outstanding (in shares)	113,935,605	101,147,225	78,724,912
Net effect of dilutive equity awards (in shares)	0	251,100	189,120
Net effect of assumed convertible notes conversion to common shares (in shares)	0	35,382,269	31,113,738
Diluted weighted average common shares outstanding (in shares)	113,935,605	136,780,594	110,027,770
Diluted earnings per common share (in dollars per share)	$ (5.12)	$ 1.46	$ 1.34