Stock-Based Compensation (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Assumptions used to value options granted [Abstract]
Dividend yield (in hundreths)	0.00%	0.00%
Annual risk free rate of return (in hundreths)	0.80%	0.90%
Expected volatility (in hundreths)	47.00%	58.70%
Expected term (years)	4 years 2 months 12 days	4 years 3 months 18 days
Weighted Average Grant Date Fair Value [Abstract]
Unrecognized compensation expense	$ 104,009,000
Weighted average period of unrecognized compensation expense (in years)	3 years
Stock Options [Member]
Number of options outstanding [Roll forward]
Balances (in shares)	2,034,000
Granted (in shares)	2,000
Exercised (in shares)	947,000
Forfeited, cancelled or expired (in shares)	22,000
Balances (in shares)	1,067,000
Options vested and expected to vest (in shares)	1,037,000
Options vested (in shares)	773,000
Weighted Average Exercise Price [Abstract]
Balances (in dollars per share)	$ 17.09
Granted (in dollars per share)	$ 32.99
Exercised (in dollars per share)	$ 13.08
Forfeited, cancelled or expired (in dollars per share)	$ 27.65
Balances (in dollars per share)	$ 20.46
Options vested and expected to vest (in dollars per share)	$ 20.15
Options vested (in dollars per share)	$ 17.00
Weighted Average Contractual Term (Years) [Abstract]
Ending balance (in years)	5 years 9 months 18 days
Options vested and expected to vest at end of period (in years)	5 years 8 months 12 days
Options vested at end of period (in years)	4 years 9 months 18 days
Aggregate Intrinsic Value [Abstract]
Ending balance	25,898,000
Options vested and expected to vest at end of period	25,488,000
Options vested at end of period	21,268,000
Weighted average grant-date fair value (in dollars per share)	$ 12.55
Total intrinsic value of options exercised	27,628,000
Weighted Average Grant Date Fair Value [Abstract]
Net cash proceeds from the exercise of stock options	$ 12,390,000
Restricted Stock Units (RSUs) [Member]
Restricted Stock Units & Awards [Roll forward]
Awarded and unvested, beginning of period (in shares)	3,252,000
Granted (in shares)	1,268,000
Vested (in shares)	(664,000)
Forfeited (in shares)	(58,000)
Awarded and unvested, ending period (in shares)	3,798,000
Restricted stock units expected to vest, Ending period (in shares)	3,250,000
Weighted Average Grant Date Fair Value [Abstract]
Awarded and unvested, beginning period (in dollars per share)	$ 31.10
Granted (in dollars per share)	$ 41.33
Vested (in dollars per share)	$ 28.66
Forfeited (in dollars per share)	$ 34.69
Awarded and unvested, ending period (in dollars per share)	$ 34.89
Restricted Stock Units (RSUs) [Member] | Equity Incentive Plan 2006 [Member]
Restricted Stock Units & Awards [Roll forward]
Granted (in shares)	355,000
Restricted Stock Units (RSUs) [Member] | Minimum [Member] | Equity Incentive Plan 2006 [Member]
Assumptions used to value options granted [Abstract]
Vesting period of restricted stock	3 years
Restricted Stock Units (RSUs) [Member] | Maximum [Member] | Equity Incentive Plan 2006 [Member]
Assumptions used to value options granted [Abstract]
Vesting period of restricted stock	4 years
Performance Based Restricted Stock [Member] | Equity Incentive Plan 2006 [Member]
Assumptions used to value options granted [Abstract]
Vesting period of restricted stock	3 years