Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net income	$ 273,706	$ 289,788
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment and amortization of other intangible assets	46,554	47,924
Stock-based compensation	34,351	34,281
Excess tax benefit associated with stock-based compensation	(19,420)	(8,566)
Unrealized Gain (Loss) on Derivatives	9,058	(3,953)
Contingent interest payment for debenture	(10,759)	0
Other, net	8,161	7,470
Changes in operating assets and liabilities
Accounts receivable	(1,319)	(2,550)
Prepaid expenses and other assets	2,967	31,349
Accounts payable and accrued liabilities	14,658	(2,540)
Deferred revenues	49,787	37,237
Deferred Income Taxes	55,203	36
Net cash provided by operating activities	462,947	430,476
Net Cash Provided By Used In Investing Activities Abstract
Proceeds from maturities and sales of marketable securities	1,965,767	2,425,259
Purchases of marketable securities	(2,443,865)	(2,281,523)
Purchases of property and equipment	(28,659)	(30,058)
Other investing activities	(3,666)	351
Net cash used in investing activities	(510,423)	114,029
Cash flows from financing activities:
Proceeds from issuance of common stock from option exercises and employee stock purchase plans	14,690	15,816
Repurchases of common stock	(492,575)	(673,540)
Proceeds from Issuance of Senior Long-term Debt	492,237	0
Excess tax benefit associated with stock-based compensation	19,420	8,566
Net cash used in financing activities	33,772	(649,158)
Effect of exchange rate changes on cash and cash equivalents	(33)	(621)
Net decrease in cash and cash equivalents	(13,737)	(105,274)
Cash and cash equivalents at beginning of period	191,608	339,223
Cash and cash equivalents at end of period	177,871	233,949
Supplemental cash flow disclosures:
Cash paid for interest, net of capitalized interest	68,678	57,767
Cash paid for income taxes, net of refunds received	$ 13,289	$ 34,937