Stock Compensation Stock Compensation Shares Authorized under Stock Option Plans by Exercise Price Range (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding (in shares)	2,285,640	2,308,004	2,537,601	2,550,048
Outstanding, Weighted Average Remaining Contractual Term	6 years 7 months 6 days	7 years 7 months 6 days	6 years	6 years 7 months 6 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 13.12	$ 13.10	$ 12.74	$ 12.53
Options exercisable (in shares)	398,437	391,859	1,118,264
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 12.88
Exercise Price Range $0.00 to $12.73 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 0.00
Range of Exercise Prices, Maximum (in dollars per share)	$ 12.73
Options Outstanding (in shares)	1,602,731
Outstanding, Weighted Average Remaining Contractual Term	6 years 3 months 18 days
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 12.22
Options exercisable (in shares)	306,191
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 12.41
Exercise Price Range $12.73 to $15.28 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 12.73
Range of Exercise Prices, Maximum (in dollars per share)	$ 15.28
Options Outstanding (in shares)	206,629
Outstanding, Weighted Average Remaining Contractual Term	6 years
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 14.33
Options exercisable (in shares)	92,246
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 14.44
Exercise Price Range $15.28 to $17.82 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, Minimum (in dollars per share)	$ 15.28
Range of Exercise Prices, Maximum (in dollars per share)	$ 17.82
Options Outstanding (in shares)	476,280
Outstanding, Weighted Average Remaining Contractual Term	8 years
Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 15.65
Options exercisable (in shares)	0
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 0.00