Stock-based Compensation Stock-based Compensation (Details 5) (Stock options, USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012 Years
Stock options
Shares
Outstanding, beginning of period (in shares)	6,570
Granted (in shares)	638
Exercised (in shares)	(405)
Forfeited (in shares)	(125)
Outstanding, end of period (in shares)	6,678
Exercisable, end of period (in shares)	5,767
Vested and expected to vest, end of period (in shares)	6,632
Weighted Average Exercise Price
Outstanding, beginning of period (in dollars per share)	$ 20.73
Granted (in dollars per share)	$ 22.30
Exercised (in dollars per share)	$ 7.74
Forfeited (in dollars per share)	$ 24.41
Outstanding, end of period (in dollars per share)	$ 21.60
Exercisable, end of period (in dollars per share)	$ 20.76
Vested and expected to vest, end of period (in dollars per share)	$ 21.56
Weighted-Average Remaining Contractual Term (in years)
Outstanding, beginning of period (in years)	5.0
Outstanding, end of period (in years)	5.0
Exercisable, end of period (in years)	4.4
Vested and expected to vest, end of period (in years)	5.0
Aggregate Intrinsic Value
Outstanding, end of period	$ 15,662
Exercisable, end of period	15,661
Vested and expected to vest, end of period	$ 15,662