Stock-Based Compensation (Schedule of Stock Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 90,585	$ 61,305	$ 76,468
Less: Income tax benefit	(33,126)	(21,212)	(26,566)
Provision for income taxes	(33,126)	(21,212)	(26,566)
Total stock-based compensation, net of taxes	57,459	40,093	49,902
Stock Based Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	14,244	13,533	15,154
Deferred Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	1,885	1,885	1,885
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	77,882	47,807	62,928
1999 ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	5,850	5,553	4,319
Capitalized Internal Use Software [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	(9,276)	(7,473)	(7,818)
Cost of Revenue [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Effect of stock-based compensation on income	2,871	2,360	2,806
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Effect of stock-based compensation on income	17,275	11,125	14,539
Sales and Marketing Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Effect of stock-based compensation on income	42,760	27,990	35,525
General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Effect of stock-based compensation on income	$ 27,679	$ 19,830	$ 23,598