Equity - Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income attributable to Redwood	$ 30,933	$ 36,180	$ 36,324	$ 36,969	$ 25,355	$ 52,553	$ 41,281	$ 12,063	$ 140,406	$ 131,252	$ 102,088
Less: Dividends and undistributed earnings allocated to participating securities									(3,632)	(3,742)	(2,806)
Net income allocated to common shareholders									$ 136,774	$ 127,510	$ 99,282
Basic weighted average common shares outstanding (in shares)									76,792,957	76,747,047	82,945,103
Basic earnings per common share (in dollars per share)	$ 0.39	$ 0.46	$ 0.46	$ 0.47	$ 0.32	$ 0.67	$ 0.52	$ 0.15	$ 1.78	$ 1.66	$ 1.20
Less: Dividends and undistributed earnings allocated to participating securities									$ (3,836)	$ (4,035)	$ (2,677)
Add back: Interest expense on convertible notes for the period, net of tax									26,898	23,862	0
Net income allocated to common shareholders									$ 163,468	$ 151,079	$ 99,411
Net effect of dilutive equity awards (in shares)									185,383	28,435	1,573,292
Net effect of assumed convertible notes conversion to common shares (in shares)									24,996,668	21,133,608	0
Diluted weighted average common shares outstanding (in shares)									101,975,008	97,909,090	84,518,395
Diluted earnings per common share (in dollars per share)	$ 0.35	$ 0.41	$ 0.43	$ 0.43	$ 0.31	$ 0.58	$ 0.48	$ 0.15	$ 1.60	$ 1.54	$ 1.18