Stock-Based Compensation - Outstanding Stock Options (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, shares	222,273
Outstanding (in dollars per share)	$ 15.44
Outstanding, remaining term	3 years 1 month 6 days
Outstanding, intrinsic value	$ 313,474,000
Vested and expected to vest, shares	222,210
Vested and expected to vest (in dollars per share)	$ 15.44
Vested and expected to vest, remaining term	3 years 1 month 6 days
Vested and expected to vest, intrinsic value	$ 313,319,000
Exercisable, shares	217,503
Exercisable (in dollars per share)	$ 15.60
Exercisable, remaining term	3 years
Exercisable, intrinsic value	$ 301,835,000
Options exercises in period, intrinsic value	100,000
Proceeds from stock options exercised	200,000
Options, vested in period, fair value	$ 0	$ 0	$ 200,000
Zero to Ten Dollars
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, shares	119,093
Outstanding (in dollars per share)	$ 7.72
Outstanding, remaining term	4 years 7 months 6 days
Outstanding, intrinsic value	$ 0
Ten Dollars to Twenty Dollars
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, shares	14,634
Outstanding (in dollars per share)	$ 16.28
Outstanding, remaining term	1 year 10 months 24 days
Outstanding, intrinsic value	$ 0
Twenty Dollars to Thirty Dollars
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, shares	88,546
Outstanding (in dollars per share)	$ 25.68
Outstanding, remaining term	1 year 4 months 24 days
Outstanding, intrinsic value	$ 0