Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities:
Net income (loss)	$ (108,173)	$ (121,510)	$ (225,900)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	41,770	54,315	82,894
Stock-based expense	107,461	131,575	129,233
(Gain) loss from sales of investments, assets and other, net	26	(5,558)	(1,610)
Tax benefits (costs) from stock-based awards		989	(86)
Excess tax (benefits) costs from stock-based awards		(989)	86
Accretion and amortization on marketable securities	323	5,711	10,061
Change in deferred income taxes and other	(1,988)	(12,693)	(10,982)
Impairment of intangible assets	20,677
Changes in operating assets and liabilities:
Accounts receivable, net	3,834	10,148	(16,489)
Income tax receivable	2,425	(1,929)	5,433
Other assets	(4,926)	(16,167)	971
Accounts payable	(3,613)	10,934	(6,393)
Deferred revenue	13,113	(64,762)	3,643
Income tax payable	1,889
Other liabilities	(12,802)	(34,511)	24,628
Net cash provided by (used in) operating activities	60,016	(44,447)	(4,511)
Investing activities:
Purchases of marketable securities		(101,091)	(758,509)
Sales and maturities of marketable securities	244,837	867,198	806,232
Acquisition of property and equipment	(10,313)	(7,832)	(9,201)
Business acquisitions, net of cash acquired	(33,630)	(20,023)	(392,411)
Proceeds from sale of property and equipment	3,209	814	5,059
Proceeds from sale of equity method investment		10,507
Other investing activities, net			4,671
Net cash provided by (used in) investing activities	204,103	749,573	(344,159)
Financing activities:
Taxes paid related to net share settlement of equity awards	(3,422)	(2,902)	(1,216)
Repurchases of common stock	(142,596)	(88,409)
Proceeds from employee stock purchase plan and exercise of stock options	5,921	7,567	16,421
Excess tax benefits (costs) from stock-based awards		989	(86)
Acquisition-related contingent consideration payment	(10,230)	(10,790)
Net cash provided by (used in) financing activities	(150,327)	(93,545)	15,119
Effect of exchange rate changes on cash and cash equivalents	(3,542)	(667)	(669)
Net increase (decrease) in cash and cash equivalents	110,250	610,914	(334,220)
Cash and cash equivalents, beginning of period	742,217	131,303	465,523
Cash and cash equivalents, end of period	$ 852,467	$ 742,217	$ 131,303