Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities:
Net income (loss)	$ (9,474)	$ (26,558)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	8,881	10,812
Stock-based expense	17,526	29,608
(Gain) loss from sales of investments, assets and other, net	38	11
Accretion and amortization on marketable securities		259
Change in deferred income taxes and other	1,075	1,422
Changes in operating assets and liabilities:
Accounts receivable, net	(8,964)	7,217
Income tax receivable	20	595
Other assets	(5,923)	(1,812)
Accounts payable	(8,802)	(12,818)
Deferred revenue	13,074	(5,096)
Income tax payable	1,252
Other liabilities	(13,422)	(6,945)
Net cash provided by (used in) operating activities	(4,719)	(3,305)
Investing activities:
Sales and maturities of marketable securities		118,900
Acquisition of property and equipment	(2,285)	(2,654)
Business acquisitions, net of cash acquired	(35,081)	(12,500)
Proceeds from sale of property and equipment	15	398
Other investing activities, net	(7,390)
Net cash provided by (used in) investing activities	(44,741)	104,144
Financing activities:
Taxes paid related to net share settlement of equity awards	(415)	(919)
Repurchases of common stock	(86,164)	(112,392)
Proceeds from employee stock purchase plan and exercise of stock options	3,152	2,476
Net cash provided by (used in) financing activities	(83,427)	(110,835)
Effect of exchange rate changes on cash and cash equivalents	857	(770)
Net increase (decrease) in cash and cash equivalents	(132,030)	(10,766)
Cash and cash equivalents, beginning of period	852,467	742,217
Cash and cash equivalents, end of period	$ 720,437	$ 731,451