Stock Based Compensation (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Stock Options [Member]
Number of options outstanding [Roll forward]
Balances (in shares)	2,768,000
Granted (in shares)	43,000
Exercised (in shares)	(190,000)
Forfeited, cancelled or expired (in shares)	(23,000)
Balances (in shares)	2,598,000
Options vested and expected to vest (in shares)	2,500,000
Options vested (in shares)	2,093,000
Weighted Average Exercise Price [Abstract]
Balances (in dollars per share)	$ 15.71
Granted (in dollars per share)	$ 27.00
Exercised (in dollars per share)	$ 17.63
Forfeited, cancelled or expired (in dollars per share)	$ 20.38
Balances (in dollars per share)	$ 15.71
Options vested and expected to vest (in dollars per share)	$ 15.41
Options vested (in dollars per share)	$ 13.28
Weighted Average Contractual Term (Years) [Abstract]
Ending balance (in years)	6.1
Options vested and expected to vest at end of period (in years)	6.0
Options vested at end of period (in years)	5.5
Aggregate Intrinsic Value [Abstract]
Ending balance	$ 43,498,000
Options vested and expected to vest at end of period	42,310,000
Options vested at end of period	38,053,000
Assumptions used to value options granted [Abstract]
Dividend yield (in hundreths)	0.00%	0.00%
Annual risk free rate of return (in hundreths)	0.90%	2.10%
Expected volatility (in hundreths)	58.70%	48.10%
Expected term (years)	4.3	4.5
Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant-date fair value (in dollars per share)	$ 12.66
Net cash proceeds from the exercise of stock options	3,345,000
Total intrinsic value of options exercised	2,411,000
Restricted Stock Units (RSUs) [Member]
Restricted Stock Units & Awards [Roll forward]
Awarded and unvested, beginning of period (in shares)	1,969,000
Granted (in shares)	1,395,000
Vested (in shares)	(609,000)
Forfeited (in shares)	(72,000)
Awarded and unvested, ending period (in shares)	2,683,000
Restricted stock units expected to vest, Ending period (in shares)	2,211,000
Weighted Average Grant Date Fair Value [Abstract]
Awarded and unvested, beginning period (in dollars per share)	$ 31.33
Granted (in dollars per share)	$ 27.60
Vested (in dollars per share)	$ 21.13
Forfeited (in dollars per share)	$ 34.80
Awarded and unvested, ending period (in dollars per share)	$ 31.61
Vesting period of restricted stock, minimum (in years)	3
Vesting period of restricted stock, maximum (in years)	4
Unrecognized compensation expense	$ 80,081,000
Weighted-average period of unrecognized compensation expense (in years)	3
Number of restricted stock units with both performance and service vesting criteria	445,000