CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 8,824	$ 10,425
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	397	76
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0	258
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	397	(182)
Unrealized losses on available-for-sale securities	(11)	(7)
Comprehensive income	$ 9,210	$ 10,236