Summary of Significant Accounting Policies (Details) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Summary of Significant Accounting Policies [Line Items]
Estimated annual effective tax rate	40.00%
Effective tax rate	25.00%
Foreign withholding taxes	$ 11,890,000	$ 7,586,000
U.S. federal statutory rate		35.00%
Excess tax benefits from stock-based compensation	7,554,000	1,730,000
Cash paid for income taxes	12,300,000
Operating loss carryforwards, federal			69,062,000
Operating loss carryforwards, state			61,493,000
Business acquisition deferred tax asset	1,900,000
Income tax benefit from release of valuation allowance	10,237,000	0
Change in deferred tax liability, business acquisition	$ 8,300,000
Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Vesting period of equity awards	2 years
Useful life of patents and patent rights	1 year
Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Vesting period of equity awards	4 years
Useful life of patents and patent rights	9 years