Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 171,403	$ 136,481
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment and amortization of other intangible assets	30,526	26,273
Stock-based compensation	16,429	16,584
Excess tax benefit associated with stock-based compensation	(17,642)	(11,638)
Deferred Income Taxes	16,055	19,135
Other, net	10,064	10,947
Changes in operating assets and liabilities
Accounts receivable	(2,263)	2,213
Prepaid expenses and other assets	(991)	2,955
Accounts payable and accrued liabilities	30,090	(32,879)
Deferred revenues	43,802	75,178
Net cash provided by operating activities	297,473	245,249
Cash flows from investing activities:
Proceeds from maturities and sales of marketable securities	1,564,459	8,101
Purchases of marketable securities	(1,557,724)	(1,097,669)
Purchases of property and equipment	(37,550)	(26,242)
Other investing activities	(3,221)	(520)
Net cash used in investing activities	(34,036)	(1,116,330)
Cash flows from financing activities:
Proceeds from issuance of common stock from option exercises and employee stock purchase plans	9,396	15,348
Repurchases of common stock	(478,148)	(152,725)
Repayments of borrowings	100,000	0
Proceeds from Issuance of Senior Notes, net of issuance costs	738,731	0
Excess tax benefit associated with stock-based compensation	17,642	11,638
Other financing activities	0	189
Net cash used in financing activities	187,621	(125,550)
Effect of exchange rate changes on cash and cash equivalents	(3,493)	(1,097)
Net decrease in cash and cash equivalents	447,565	(997,728)
Cash and cash equivalents at beginning of period	130,736	1,313,349
Cash and cash equivalents at end of period	578,301	315,621
Supplemental cash flow disclosures:
Cash paid for interest, net of capitalized interest	20,495	20,476
Cash paid for income taxes, net of refunds received	$ 17,531	$ 21,193