Other Comprehensive Income (Loss) - Other comprehensive income (loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other comprehensive income (loss), before tax amount
Other comprehensive income (loss), before tax amount	$ 1,051	$ (1,880)	$ (431)
Other comprehensive income (loss), tax (expense) benefit
Other comprehensive income (loss), tax (expense) benefit	(195)	124	532
Other comprehensive income (loss):
Total other comprehensive income (loss), net of tax	856	(1,756)	101
Foreign Currency Translation Adjustment
Other comprehensive income (loss), before tax amount
Other comprehensive income (loss), before reclassifications, before tax	223	(1,343)	1,027
Other comprehensive income (loss):
Other comprehensive income (loss), before reclassifications, net of tax	223	(1,343)	1,027
Unrealized/Recognized Gains (Losses)
Other comprehensive income (loss), before tax amount
Other comprehensive income (loss), before reclassifications, before tax	1,127	(529)	9,671
Amounts reclassified from accumulated other comprehensive income (loss), before tax	(299)	(8)	(11,129)
Other comprehensive income (loss), tax (expense) benefit
Other comprehensive income (loss), before reclassifications, tax (expense) benefit	(265)	122	(3,525)
Amounts reclassified from accumulated other comprehensive income (loss), tax (expense) benefit	70	2	4,057
Other comprehensive income (loss):
Other comprehensive income (loss), before reclassifications, net of tax	862	(407)	6,146
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	$ (229)	$ (6)	$ (7,072)