Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 236,841	$ 213,138
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	179,643	134,455
Stock-based compensation	84,800	72,211
Provision for doubtful accounts	1,517	889
Excess tax benefits from stock-based compensation	(23,958)	(18,152)
Provision for deferred income taxes	10,622	0
Amortization of debt discount and issuance costs	10,939	0
Loss (gain) from disposal of property and equipment	325	(15)
Loss on investments	393	0
Change in fair value of contingent consideration	300	0
Gain from divestiture of a business	0	(1,188)
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(50,213)	(51,321)
Prepaid expenses and other current assets	(22,346)	(9,266)
Accounts payable and accrued expenses	36,876	43,730
Deferred revenue	7,688	10,991
Other current liabilities	(703)	32
Other non-current assets and liabilities	(10,195)	(3,328)
Net cash provided by operating activities	462,529	392,176
Cash flows from investing activities:
Cash paid for acquired businesses, net of cash acquired	(386,532)	(27,420)
Purchases of property and equipment	(142,466)	(142,567)
Capitalization of internal-use software development costs	(83,841)	(55,171)
Purchases of short- and long-term marketable securities	(1,068,198)	(403,556)
Proceeds from sales of short- and long-term marketable securities	354,313	79,207
Proceeds from maturities of short- and long-term marketable securities	277,109	265,495
Proceeds from the sale of property and equipment	802	761
Other non-current assets and liabilities	6,420	(3,320)
Net cash used in investing activities	(1,042,393)	(286,571)
Cash flows from financing activities:
Proceeds from the issuance of convertible senior notes, net of issuance costs	678,735	0
Proceeds from the issuance of warrants related to convertible senior notes	77,970	0
Purchase of note hedge related to convertible senior notes	(101,292)	0
Repayment of acquired debt and capital leases	(17,862)	0
Payment of contingent consideration related to acquired business	1,575	0
Proceeds related to the issuance of common stock under stock plans	75,361	54,418
Excess tax benefits from stock-based compensation	23,958	18,152
Employee taxes paid related to net share settlement of stock-based awards	(43,205)	(28,559)
Repurchases of common stock	(226,513)	(112,408)
Net cash provided by (used in) financing activities	465,577	(68,397)
Effects of exchange rate changes on cash and cash equivalents	(5,265)	(4,182)
Net (decrease) increase in cash and cash equivalents	(119,552)	33,026
Cash and cash equivalents at beginning of period	333,891	201,989
Cash and cash equivalents at end of period	214,339	235,015
Supplemental disclosure of cash flow information:
Cash paid for income taxes	117,723	44,191
Non-cash financing and investing activities:
Purchases of property and equipment and capitalization of internal-use software development costs included in accounts payable and accrued expenses	40,131	12,630
Capitalization of stock-based compensation	11,577	9,252
Convertible note receivable received for divestiture of a business	$ 0	$ 18,882