Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 25,970	$ 54,387	$ 15,902
Other comprehensive loss, net of tax
Net unrealized loss on investments, net of tax	(400)	(354)	0
Other comprehensive loss, net of tax	(400)	(354)	0
Total comprehensive income	$ 25,570	$ 54,033	$ 15,902