Share-Based Compensation (Details 6) - Share-Based Compensation Expense (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	$ 59,645,000	$ 41,546,000	$ 28,773,000
Less: Income tax benefit	(20,080,000)	(15,477,000)	(9,890,000)
Total share-based compensation expense, net of tax	39,565,000	26,069,000	18,883,000
Share-Based Compensation, Aggregate Disclosures
Total unrecognized compensation cost related to restricted stock, options and the ESPP ($)	173,000,000
Remaining weighted-average period over which the unrecognized compensation cost related to restricted stock, options and the ESPP will be amortized on a straight line basis	2 years 3 months
Cost of revenue
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	12,584,000	9,592,000	7,482,000
Research and development
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	8,168,000	4,856,000	2,975,000
Sales and marketing
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	7,317,000	6,379,000	2,408,000
General and administrative
Allocation of share-based compensation expense to income statement line items
Pre-tax share-based compensation	$ 31,576,000	$ 20,719,000	$ 15,908,000