Stockholders' Equity - AOCI Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in the balances of each component of AOCI
Balance at the beginning of the period	$ 437,775	$ 840,093	$ 601,704
Other comprehensive income (loss), net of tax	74	8	35
Balance at the end of the period	374,512	437,775	840,093
Accumulated Other Comprehensive Income
Changes in the balances of each component of AOCI
Balance at the beginning of the period	1,820	1,812	1,777
Other comprehensive income (loss), net of tax	74	8	35
Balance at the end of the period	1,894	1,820	1,812
Foreign Currency Translation
Changes in the balances of each component of AOCI
Balance at the beginning of the period	1,836	1,839	1,797
Other comprehensive income (loss), net of tax	25	(3)	42
Balance at the end of the period	1,861	1,836	1,839
Unrealized Gains (Losses) on Available for Sale Securities
Changes in the balances of each component of AOCI
Balance at the beginning of the period	(16)	(27)	(20)
Other comprehensive income (loss), net of tax	49	11	(7)
Balance at the end of the period	$ 33	$ (16)	$ (27)