Equity and Equity Compensation Plans - Compensation Costs for PSU's (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 36,973	$ 27,814	$ 20,438
Performance Restricted Stock Units
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	2,854	284	610
Performance Restricted Stock Units | Current Period
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	2,664	894	610
Performance Restricted Stock Units | Prior Periods
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 190	$ (610)	$ 0