Share-Based Compensation Arrangements (Stock Options Outstanding and Options Exercisable) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Share Options	357,477
Options Outstanding, Weighted Average Remaining Life (Years)	5 years 9 months 17 days
Options Outstanding, Weighted Average Exercise Price	$ 24.99
Options Exercisable, Number of Share Options	192,627
Options Exercisable, Weighted Average Exercise Price	$ 22.60
$16.39 to $19.66 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 16.39
Exercise Price Ranges, Upper Range Limit	$ 19.66
Options Outstanding, Number of Share Options	56,032
Options Outstanding, Weighted Average Remaining Life (Years)	4 years 11 months 20 days
Options Outstanding, Weighted Average Exercise Price	$ 17.61
Options Exercisable, Number of Share Options	56,032
Options Exercisable, Weighted Average Exercise Price	$ 17.61
$19.67 to $22.94 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 19.67
Exercise Price Ranges, Upper Range Limit	$ 22.94
Options Outstanding, Number of Share Options	40,778
Options Outstanding, Weighted Average Remaining Life (Years)	6 years 3 months 12 days
Options Outstanding, Weighted Average Exercise Price	$ 21.71
Options Exercisable, Number of Share Options	40,778
Options Exercisable, Weighted Average Exercise Price	$ 21.71
$22.95 to $26.22 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 22.95
Exercise Price Ranges, Upper Range Limit	$ 26.22
Options Outstanding, Number of Share Options	133,478
Options Outstanding, Weighted Average Remaining Life (Years)	5 years 11 months 13 days
Options Outstanding, Weighted Average Exercise Price	$ 23.62
Options Exercisable, Number of Share Options	46,078
Options Exercisable, Weighted Average Exercise Price	$ 24.06
$26.23 to $29.49 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 26.23
Exercise Price Ranges, Upper Range Limit	$ 29.49
Options Outstanding, Number of Share Options	49,739
Options Outstanding, Weighted Average Remaining Life (Years)	0 years 9 months 0 days
Options Outstanding, Weighted Average Exercise Price	$ 27.61
Options Exercisable, Number of Share Options	49,739
Options Exercisable, Weighted Average Exercise Price	$ 27.61
$29.50 to $32.77 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Ranges, Lower Range Limit	$ 29.50
Exercise Price Ranges, Upper Range Limit	$ 32.77
Options Outstanding, Number of Share Options	77,450
Options Outstanding, Weighted Average Remaining Life (Years)	9 years 1 month 13 days
Options Outstanding, Weighted Average Exercise Price	$ 32.76
Options Exercisable, Number of Share Options	0
Options Exercisable, Weighted Average Exercise Price	$ 0.00