Share-Based Compensation Arrangements (Stock Options Outstanding and Options Exercisable) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares	645,797
Options Outstanding, Weighted Average Remaining Life (Years)	5 years
Options Outstanding, Weighted Average Exercise Price	$ 23.58
Options Exercisable, Number	390,347
Options Exercisable, Weighted Average Exercise Price	$ 25.35
$14.47 to $17.36 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 14.47
Exercise Price Ranges, Upper Range Limit	$ 17.36
Options Outstanding, Number of Shares	3,582
Options Outstanding, Weighted Average Remaining Life (Years)	5 years 10 months 24 days
Options Outstanding, Weighted Average Exercise Price	$ 16.58
Options Exercisable, Number	3,582
Options Exercisable, Weighted Average Exercise Price	$ 16.58
$17.37 to $20.26 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 17.37
Exercise Price Ranges, Upper Range Limit	$ 20.26
Options Outstanding, Number of Shares	153,785
Options Outstanding, Weighted Average Remaining Life (Years)	4 years 7 months 6 days
Options Outstanding, Weighted Average Exercise Price	$ 18.54
Options Exercisable, Number	59,985
Options Exercisable, Weighted Average Exercise Price	$ 20.00
$20.27 to $23.15 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 20.27
Exercise Price Ranges, Upper Range Limit	$ 23.15
Options Outstanding, Number of Shares	68,200
Options Outstanding, Weighted Average Remaining Life (Years)	7 years
Options Outstanding, Weighted Average Exercise Price	$ 21.52
Options Exercisable, Number	12,000
Options Exercisable, Weighted Average Exercise Price	$ 20.62
$23.16 to $26.05 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 23.16
Exercise Price Ranges, Upper Range Limit	$ 26.05
Options Outstanding, Number of Shares	185,850
Options Outstanding, Weighted Average Remaining Life (Years)	7 years 8 months 12 days
Options Outstanding, Weighted Average Exercise Price	$ 23.69
Options Exercisable, Number	80,400
Options Exercisable, Weighted Average Exercise Price	$ 24.12
$26.06 to $28.94 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 26.06
Exercise Price Ranges, Upper Range Limit	$ 28.94
Options Outstanding, Number of Shares	234,380
Options Outstanding, Weighted Average Remaining Life (Years)	2 years 6 months
Options Outstanding, Weighted Average Exercise Price	$ 27.52
Options Exercisable, Number	234,380
Options Exercisable, Weighted Average Exercise Price	$ 27.52