Equity Compensation Plans - Unrecognized Compensation Cost (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized [Roll Forward]
Unrecognized compensation cost at beginning of period	$ 32,328
Equity grants	10,629
Performance-based valuation adjustment	(7,352)
Equity grant forfeitures	(8,071)
Equity compensation expense	(7,896)
Unrecognized Compensation Cost at End of Period	19,638
Redwood Incentive Plan | Restricted Stock Awards
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized [Roll Forward]
Unrecognized compensation cost at beginning of period	1,990
Equity grants	108
Performance-based valuation adjustment	0
Equity grant forfeitures	(529)
Equity compensation expense	(807)
Unrecognized Compensation Cost at End of Period	762
Redwood Incentive Plan | Restricted Stock Units
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized [Roll Forward]
Unrecognized compensation cost at beginning of period	3,534
Equity grants	3,581
Performance-based valuation adjustment	0
Equity grant forfeitures	(2,161)
Equity compensation expense	(1,067)
Unrecognized Compensation Cost at End of Period	3,887
Redwood Incentive Plan | Deferred Stock Units
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized [Roll Forward]
Unrecognized compensation cost at beginning of period	17,858
Equity grants	6,780
Performance-based valuation adjustment	0
Equity grant forfeitures	(4,733)
Equity compensation expense	(6,268)
Unrecognized Compensation Cost at End of Period	13,637
Redwood Incentive Plan | Performance Stock Units
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized [Roll Forward]
Unrecognized compensation cost at beginning of period	8,946
Equity grants	0
Performance-based valuation adjustment	(7,352)
Equity grant forfeitures	(648)
Equity compensation expense	326
Unrecognized Compensation Cost at End of Period	1,272
Employee Stock Purchase Plan
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized [Roll Forward]
Unrecognized compensation cost at beginning of period	0
Equity grants	160
Performance-based valuation adjustment	0
Equity grant forfeitures	0
Equity compensation expense	(80)
Unrecognized Compensation Cost at End of Period	$ 80