UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities:
Net (loss) income	$ (28,717)	$ 12,200
Adjustments to reconcile net (loss) income to cash provided by operating activities:
Stock-based compensation	18,350	15,109
Amortization and depreciation	18,774	10,322
Foreign currency transaction loss	3,712	1,085
Other non-cash	1,471	1,137
Change in operating assets and liabilities, net	9,113	15,802
Cash provided by operating activities	22,703	55,655
Investing activities:
Purchases of investments	(7,224)	(35,204)
Proceeds from maturities and called investments	8,548	5,995
Other	(2,790)	(2,069)
Cash used in investing activities	(1,466)	(31,278)
Financing activities:
Dividend payments to shareholders	(2,363)	(2,344)
Common stock repurchases	(23,224)	(20,708)
Cash used in financing activities	(25,587)	(23,052)
Effect of exchange rate changes on cash and cash equivalents	295	2,186
Net (decrease) increase in cash and cash equivalents	(4,055)	3,511
Cash and cash equivalents, beginning of period	114,422	162,279
Cash and cash equivalents, end of period	$ 110,367	$ 165,790