Stock-Based Compensation (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2011 Year
Range 9.56 to 11.50
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	671,172
Options Outstanding, Average Remaining Life (Years)	6.39
Options Outstanding, Average Exercise Price	$ 11.35
Options Exercisable, Number of Shares	435,150
Options Exercisable, Average Exercise Price	$ 11.30
Range of Exercise Prices, Lower Range Limit	$ 9.56
Range of Exercise Prices, Upper Range Limit	$ 11.50
Range 12.62 to 18.63
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	706,006
Options Outstanding, Average Remaining Life (Years)	6.23
Options Outstanding, Average Exercise Price	$ 15.54
Options Exercisable, Number of Shares	393,969
Options Exercisable, Average Exercise Price	$ 15.73
Range of Exercise Prices, Lower Range Limit	$ 12.62
Range of Exercise Prices, Upper Range Limit	$ 18.63
Range 19.13 to 22.34
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	990,620
Options Outstanding, Average Remaining Life (Years)	6.40
Options Outstanding, Average Exercise Price	$ 21.11
Options Exercisable, Number of Shares	603,954
Options Exercisable, Average Exercise Price	$ 21.41
Range of Exercise Prices, Lower Range Limit	$ 19.13
Range of Exercise Prices, Upper Range Limit	$ 22.34
Range 23.26 to 33.45
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	269,505
Options Outstanding, Average Remaining Life (Years)	5.68
Options Outstanding, Average Exercise Price	$ 26.34
Options Exercisable, Number of Shares	243,334
Options Exercisable, Average Exercise Price	$ 26.47
Range of Exercise Prices, Lower Range Limit	$ 23.26
Range of Exercise Prices, Upper Range Limit	$ 33.45