Stock-Based Compensation (Details 2) (Stock options, USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock options
Stock option activity
Options outstanding at the beginning of the period (in shares)	6,296,000
Granted (in shares)	958,000
Cancelled / Forfeitures (in shares)	(977,000)
Exercised (in shares)	(1,673,000)	(2,100,000)	(2,700,000)
Options outstanding at the end of the period (in shares)	4,604,000	6,296,000
Options expected to vest at the end of the period (in shares)	1,728,000
Options exercisable at the end of the period (in shares)	2,905,000
Stock options, Weighted Average Exercise Price
Options outstanding at the beginning of the period (in dollars per share)	$ 11.07
Granted (in dollars per share)	$ 27.76
Cancelled / Forfeitures (in dollars per shares)	$ 20.92
Exercised (in dollars per share)	$ 7.19
Options outstanding at the end of the period (in dollars per share)	$ 14.11	$ 11.07
Options expected to vest at the end of the period (in dollars per share)	$ 22.83
Options exercisable at the end of the period (in dollars per share)	$ 8.90
Stock options, Weighted Average Remaining Contractual Terms
Options outstanding at the end of the period	4 years 6 months 25 days
Options expected to vest at the end of the period	6 years 4 months 6 days
Options exercisable at the end of the period	3 years 6 months 4 days
Stock options, Aggregate Intrinsic Value
Options outstanding at the end of the period	$ 57,588
Options expected to vest at the end of the period	9,752
Options exercisable at the end of the period	$ 54,382
Assumptions used to determine fair value of options granted
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Risk-free interest rate (as a percent)	0.55%	0.86%	1.51%
Expected volatility (as a percent)	40.13%	42.74%	43.80%
Expected life	4 years 5 months 19 days	4 years 6 months 25 days	4 years