Equity - Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Basic Earnings (Loss) per Common Share:
Net income (loss) attributable to Redwood	$ 141,812	$ 34,310	$ (636,142)	$ 120,040
Less: Dividends and undistributed earnings allocated to participating securities	(4,067)	(856)	(1,427)	(3,260)
Net income (loss) allocated to common shareholders	$ 137,745	$ 33,454	$ (637,569)	$ 116,780
Basic weighted average common shares outstanding (in shares)	113,403,102	101,872,126	113,952,308	97,214,064
Basic Earnings (Loss) per Common Share (in dollars per share)	$ 1.21	$ 0.33	$ (5.60)	$ 1.20
Diluted Earnings (Loss) per Common Share:
Net income (loss) attributable to Redwood	$ 141,812	$ 34,310	$ (636,142)	$ 120,040
Less: Dividends and undistributed earnings allocated to participating securities	(3,512)	(1,036)	(1,427)	(3,625)
Adjust for interest expense and gain on extinguishment of convertible notes for the period, net of tax	6,990	8,887	0	26,271
Net income (loss) allocated to common shareholders	$ 145,290	$ 42,161	$ (637,569)	$ 142,686
Weighted average common shares outstanding (in shares)	113,403,102	101,872,126	113,952,308	97,214,064
Net effect of dilutive equity awards (in shares)	0	362,743	0	261,155
Net effect of assumed convertible notes conversion to common shares (in shares)	28,566,875	34,287,840	0	33,727,470
Diluted weighted average common shares outstanding (in shares)	141,969,977	136,522,709	113,952,308	131,202,689
Diluted Earnings (Loss) per Common Share (in dollars per share)	$ 1.02	$ 0.31	$ (5.60)	$ 1.09