Accumulated Other Comprehensive Income (Loss), Net of Tax (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax:
Balance at beginning of period	$ 23,473
Current period change	140
Balance at end of period	22,611
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax:
Balance at beginning of period	(1,818)
Current period change	140
Balance at end of period	(1,678)
Unrealized gain (loss) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss), Net of Tax:
Balance at beginning of period	(3)
Current period change	0
Balance at end of period	(3)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax:
Balance at beginning of period	(1,821)
Balance at end of period	$ (1,681)