Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$ 88,238	$ 94,423
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment and amortization of other intangible assets	15,747	16,008
Stock-based compensation	10,128	9,993
Excess tax benefit associated with stock-based compensation	(5,993)	0
Unrealized Gain (Loss) on Derivatives	7,019	(5,269)
contingent interest payment for debenture	(5,225)	0
Other, net	2,701	1,004
Changes in operating assets and liabilities
Accounts receivable	(1,282)	(1,806)
Prepaid expenses and other assets	(3,084)	7,925
Accounts payable and accrued liabilities	(28,816)	(34,579)
Deferred revenues	34,582	30,384
Deferred Income Taxes	18,654	23,546
Net cash provided by operating activities	132,669	141,629
Cash flows from investing activities:
Proceeds from maturities and sales of marketable securities	325,399	718,177
Purchases of marketable securities	(257,415)	(784,090)
Purchases of property and equipment	(13,042)	(11,262)
Other investing activities	(3,787)	34
Net cash used in investing activities	51,155	(77,141)
Cash flows from financing activities:
Proceeds from issuance of common stock from option exercises and employee stock purchase plans	8,776	8,668
Repurchases of common stock	(178,330)	(145,556)
Proceeds from Issuance of Senior Long-term Debt	493,824	0
Excess tax benefit associated with stock-based compensation	5,993	0
Net cash used in financing activities	330,263	(136,888)
Effect of exchange rate changes on cash and cash equivalents	184	230
Net decrease in cash and cash equivalents	514,271	(72,170)
Cash and cash equivalents at beginning of period	191,608	339,223
Cash and cash equivalents at end of period	705,879	267,053
Supplemental cash flow disclosures:
Cash paid for interest, net of capitalized interest	25,494	20,209
Cash paid for income taxes, net of refunds received	$ 12,970	$ 7,651