Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	$ 605,224	$ 321,673	$ 509,457
Other comprehensive income (loss)	(309)	(376)	810
Balance	643,867	605,224	321,673
Unrealized Gains (Losses) on Securities Available-for-Sale
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	(612)	(224)
Unrealized net gain (loss) on available-for-sale securities and foreign currency translation adjustments, net of tax	(292)	(388)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(178)
Other comprehensive income (loss)	(114)	(388)
Balance	(726)	(612)	(224)
Other comprehensive income (loss) before reclassification, tax	(111)	(100)
Reclassification from AOCI, tax	(61)
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	12	0
Unrealized net gain (loss) on available-for-sale securities and foreign currency translation adjustments, net of tax	(17)	12
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	0
Other comprehensive income (loss)	(17)	12
Balance	(5)	12	$ 0
Other comprehensive income (loss) before reclassification, tax	$ (6)	$ 4