Accumulated Other Comprehensive Loss (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning Balance	$ 265,849,000	$ 16,450,000
Other comprehensive (loss) income before reclassifications	(209,000)	(56,000)
Other comprehensive loss, net of tax:	(209,000)	(56,000)
Ending Balance	181,804,000	71,820,000
Reclassification from AOCI	0
Currency Translation Adjustments
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning Balance	(347,000)	(323,000)
Other comprehensive (loss) income before reclassifications	(9,000)	(66,000)
Other comprehensive loss, net of tax:	(9,000)	(66,000)
Ending Balance	(356,000)	(389,000)
Net Unrealized Gains (Losses) on Available- for-Sale Securities
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning Balance	(4,000)	(78,000)
Other comprehensive (loss) income before reclassifications	(200,000)	10,000
Other comprehensive loss, net of tax:	(200,000)	10,000
Ending Balance	(204,000)	(68,000)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive (Loss) Income [Line Items]
Beginning Balance	(351,000)	(401,000)
Other comprehensive loss, net of tax:	(209,000)	(56,000)
Ending Balance	$ (560,000)	$ (457,000)