Share-Based Compensation (Significant Ranges of Outstanding and Exercisable Options) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 13.60
Range of Exercise prices, upper range limit	$ 79.20
Options outstanding as of December 31, 2012	422,593
Weighted average remaining contractual life (years)	3 years 7 months 13 days
Weighted average exercise price	$ 33.52
Options exercisable as of December 31, 2012	361,739
Weighted average exercise price of exercisable options	$ 37.26
$13.60 - $22.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 13.60
Range of Exercise prices, upper range limit	$ 22.20
Options outstanding as of December 31, 2012	31,158
Weighted average remaining contractual life (years)	5 years 0 months 15 days
Weighted average exercise price	$ 16.84
Options exercisable as of December 31, 2012	20,388
Weighted average exercise price of exercisable options	$ 18.48
$23.80 - $23.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 23.80
Range of Exercise prices, upper range limit	$ 23.80
Options outstanding as of December 31, 2012	54,523
Weighted average remaining contractual life (years)	4 years 8 months 27 days
Weighted average exercise price	$ 23.80
Options exercisable as of December 31, 2012	39,275
Weighted average exercise price of exercisable options	$ 23.80
$25.00 - $25.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 25.00
Range of Exercise prices, upper range limit	$ 25.00
Options outstanding as of December 31, 2012	87,500
Weighted average remaining contractual life (years)	2 years 11 months 5 days
Weighted average exercise price	$ 25.00
Options exercisable as of December 31, 2012	87,500
Weighted average exercise price of exercisable options	$ 25.00
$27.60 - $27.60
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 27.60
Range of Exercise prices, upper range limit	$ 27.60
Options outstanding as of December 31, 2012	49,147
Weighted average remaining contractual life (years)	6 years 3 months 22 days
Weighted average exercise price	$ 27.60
Options exercisable as of December 31, 2012	27,414
Weighted average exercise price of exercisable options	$ 27.60
$29.00 - $33.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 29.00
Range of Exercise prices, upper range limit	$ 33.20
Options outstanding as of December 31, 2012	50,014
Weighted average remaining contractual life (years)	4 years 10 months 21 days
Weighted average exercise price	$ 31.41
Options exercisable as of December 31, 2012	38,598
Weighted average exercise price of exercisable options	$ 31.28
$34.60 - $48.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 34.60
Range of Exercise prices, upper range limit	$ 48.80
Options outstanding as of December 31, 2012	53,747
Weighted average remaining contractual life (years)	2 years 3 months 26 days
Weighted average exercise price	$ 42.93
Options exercisable as of December 31, 2012	52,060
Weighted average exercise price of exercisable options	$ 43.20
$51.20 - $54.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 51.20
Range of Exercise prices, upper range limit	$ 54.80
Options outstanding as of December 31, 2012	45,015
Weighted average remaining contractual life (years)	2 years 9 months
Weighted average exercise price	$ 50.91
Options exercisable as of December 31, 2012	45,015
Weighted average exercise price of exercisable options	$ 52.91
$55.00 - $73.40
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 55.00
Range of Exercise prices, upper range limit	$ 73.40
Options outstanding as of December 31, 2012	45,439
Weighted average remaining contractual life (years)	1 year 0 months 7 days
Weighted average exercise price	$ 64.37
Options exercisable as of December 31, 2012	45,439
Weighted average exercise price of exercisable options	$ 64.37
$74.00 - $76.40
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 74.00
Range of Exercise prices, upper range limit	$ 76.40
Options outstanding as of December 31, 2012	4,650
Weighted average remaining contractual life (years)	1 year 0 months 11 days
Weighted average exercise price	$ 74.85
Options exercisable as of December 31, 2012	4,650
Weighted average exercise price of exercisable options	$ 74.85
$79.20 - $79.20
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise prices, lower range limit	$ 79.20
Range of Exercise prices, upper range limit	$ 79.20
Options outstanding as of December 31, 2012	1,400
Weighted average remaining contractual life (years)	3 years 3 months
Weighted average exercise price	$ 79.20
Options exercisable as of December 31, 2012	1,400
Weighted average exercise price of exercisable options	$ 79.20