Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net income	$ 139,062	$ 172,129	$ 40,582
Other comprehensive income before tax and net of reclassification adjustments:
Change in fair value of available-for-sale securities		469	32
Other comprehensive income, before tax		469	32
Income tax expense related to components of other comprehensive income		183	13
Other comprehensive income, net of tax		286	19
Comprehensive income	$ 139,062	$ 172,415	$ 40,601