Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 333,948	$ 293,487	$ 203,989
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	247,406	184,431	204,163
Stock-based compensation	111,996	95,884	90,585
Provision (benefit) for doubtful accounts	1,981	1,169	(316)
Excess tax benefits from stock-based compensation	(32,238)	(22,801)	(23,015)
(Benefit) provision for deferred income taxes	(25,880)	27,343	(5,819)
Amortization of debt discount and issuance costs	15,463	0	0
Non-cash portion of restructuring charges	0	781	0
(Gain) loss on disposal of property and equipment	(159)	414	3
Loss on investments	443	0	0
Gain from divestiture of a business	0	(1,188)	0
Change in fair value of contingent consideration	300	0	0
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(58,397)	(67,184)	(2,108)
Prepaid expenses and other current assets	(60,788)	(3,842)	6,357
Accounts payable and accrued expenses	94,698	40,533	58,672
Deferred revenue	7,725	11,495	4,552
Other current liabilities	(702)	52	(3,278)
Other non-current assets and liabilities	22,274	3,334	(3,765)
Net cash provided by operating activities	658,070	563,908	530,020
Cash flows from investing activities:
Cash paid for acquisitions, net of cash acquired	(386,532)	(30,657)	(336,680)
Purchases of property and equipment	(207,159)	(187,964)	(166,773)
Capitalization of internal-use software development costs	(111,468)	(72,109)	(54,204)
Purchases of short- and long-term marketable securities	(1,225,409)	(494,885)	(752,342)
Proceeds from sales and redemptions of short- and long-term marketable securities	373,730	160,210	214,277
Proceeds from maturities of short- and long-term marketable securities	372,287	314,925	315,788
Proceeds from sale of property and equipment	1,371	827	12
Other non-current assets and liabilities	4,374	(3,455)	812
Net cash used in by investing activities	(1,178,806)	(313,108)	(779,110)
Cash flows from financing activities:
Proceeds from the issuance of convertible senior notes, net of issuance costs	678,735	0	0
Proceeds from the issuance of warrants related to convertible senior notes	77,970	0	0
Purchase of note hedge related to convertible senior notes	(101,292)	0	0
Repayment of acquired debt and capital leases	(17,862)	0	0
Payment of contingent consideration related to acquired business	(1,575)	0	0
Proceeds related to the issuance of common stock under stock plans	87,109	63,707	45,114
Excess tax benefits from stock-based compensation	32,238	22,801	23,015
Employee taxes paid related to net share settlement of stock-based awards	(50,649)	(41,332)	(34,690)
Repurchases of common stock	(268,647)	(160,419)	(141,468)
Net cash provided by (used in) financing activities	436,027	(115,243)	(108,029)
Effects of exchange rate changes on cash and cash equivalents	(10,532)	(3,655)	(89)
Net increase (decrease) in cash and cash equivalents	(95,241)	131,902	(357,208)
Cash and cash equivalents at beginning of year	333,891	201,989	559,197
Cash and cash equivalents at end of year	238,650	333,891	201,989
Supplemental disclosure of cash flow information:
Cash paid for income taxes	166,211	63,508	94,833
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	45,868	19,927	12,939
Capitalization of stock-based compensation	15,226	12,325	9,276
Convertible note receivable received for divestiture of a business	$ 0	$ 18,882	$ 0