UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net (loss)	$ (91,351)	$ (5,796)
Adjustments to reconcile net (loss) to cash (used in) provided by operating activities
Stock-based compensation	60,242	47,573
Amortization and depreciation	50,622	31,742
Deferred income taxes	(40,531)	(1,388)
Foreign currency transaction loss (gain)	3,577	(558)
Other non-cash	(363)	(1,377)
Change in operating assets and liabilities, net	4,342	(3,108)
Cash (used in) provided by operating activities	(13,462)	67,088
Investing activities
Purchases of investments	(11,182)	(68,177)
Proceeds from maturities and called investments	13,066	26,456
Sales of investments	68,937	0
Payments for acquisitions, net of cash acquired	(10,934)	0
Investment in property and equipment	(6,439)	(7,874)
Cash provided by (used in) investing activities	53,448	(49,595)
Financing activities
Dividend payments to shareholders	(7,105)	(7,067)
Common stock repurchases	(54,836)	(64,597)
Cash (used in) financing activities	(61,941)	(71,664)
Effect of exchange rate changes on cash and cash equivalents	(363)	(1,913)
Net (decrease) in cash and cash equivalents	(22,318)	(56,084)
Cash and cash equivalents, beginning of period	114,422	162,279
Cash and cash equivalents, end of period	$ 92,104	$ 106,195