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	$ 355,260us-gaap_ProfitLoss	$ 544,450us-gaap_ProfitLoss	$ 320,032us-gaap_ProfitLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment and amortization of other intangible assets	63,690us-gaap_DepreciationAndAmortization	60,655us-gaap_DepreciationAndAmortization	54,819us-gaap_DepreciationAndAmortization
Stock-based compensation	43,977us-gaap_ShareBasedCompensation	36,649us-gaap_ShareBasedCompensation	33,362us-gaap_ShareBasedCompensation
Excess tax benefit associated with stock-based compensation	(6,054)	(19,320)	(18,436)
Unrealized Gain (Loss) on Derivatives	(2,249)us-gaap_UnrealizedGainLossOnDerivatives	17,801us-gaap_UnrealizedGainLossOnDerivatives	(422)us-gaap_UnrealizedGainLossOnDerivatives
Loss (Gain) on Sale of Investments	5us-gaap_GainLossOnSaleOfInvestments	(18,861)us-gaap_GainLossOnSaleOfInvestments	(102)us-gaap_GainLossOnSaleOfInvestments
Other, net	11,353us-gaap_OtherNoncashIncomeExpense	14,182us-gaap_OtherNoncashIncomeExpense	11,505us-gaap_OtherNoncashIncomeExpense
Changes in operating assets and liabilities
Accounts receivable	(73)	(2,500)	3,327
Prepaid expenses and other assets	11,571	(2,694)	(9,344)
Accounts payable and accrued liabilities	45,419	19,065	(13,534)
Deferred revenues	34,518	43,254	84,011
Net deferred income taxes and other long term tax liabilities	43,532	(113,284)	72,412
Net cash provided by operating activities	600,949	579,397	537,630
Cash flows from investing activities:
Proceeds from maturities and sales of marketable securities	3,428,659	3,508,569	1,234,156
Purchases of marketable securities	(3,277,096)us-gaap_PaymentsToAcquireInvestments	(3,450,068)us-gaap_PaymentsToAcquireInvestments	(2,622,898)us-gaap_PaymentsToAcquireInvestments
Purchases of property and equipment	(39,327)	(65,594)	(53,023)
Other investing activities	452	(3,969)	(588)
Net cash provided by (used in) investing activities	112,688	(11,062)	(1,442,353)
Cash flows from financing activities:
Proceeds from issuance of common stock from option exercises and employee stock purchase plans	17,597	20,667	29,303
Repurchases of common stock	(883,403)	(1,035,617)	(325,680)
Proceeds received from borrowing	0	738,297	0
Repayments of borrowings	0us-gaap_RepaymentsOfShortTermDebt	(100,000)us-gaap_RepaymentsOfShortTermDebt	0us-gaap_RepaymentsOfShortTermDebt
Excess tax benefit associated with stock-based compensation	6,054	19,320	18,436
Other financing activities	0	0	189
Net cash used in financing activities	(859,752)	(357,333)	(277,752)
Effect of exchange rate changes on cash and cash equivalents	(1,500)	(2,515)	(138)
Net (decrease) increase in cash and cash equivalents	(147,615)	208,487	(1,182,613)
Cash and cash equivalents at beginning of period	339,223	130,736	1,313,349
Cash and cash equivalents at end of period	191,608	339,223	130,736
Supplemental cash flow disclosures:
Cash paid for interest, net of capitalized interest	75,088us-gaap_InterestPaidNet	58,928us-gaap_InterestPaidNet	41,276us-gaap_InterestPaidNet
Cash paid for income taxes, net of refunds received	$ 35,201us-gaap_IncomeTaxesPaidNet	$ 26,133us-gaap_IncomeTaxesPaidNet	$ 19,436us-gaap_IncomeTaxesPaidNet

Name:	us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.