Stockholders' Equity - Employee Plans Equity Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense	$ 4,100	$ 3,300	$ 3,600
Share-based Payment Arrangement, Expense, Tax Benefit	1,049	1,486		$ 2,149
Payment, Tax Withholding, Share-based Payment Arrangement	$ 400	$ 400	$ 1,100