Common Stock Plans (Stock Options, Range of Exercise Prices) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 year
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of exercisable options, Weighted Average Remaining Contractual Life (in years)	6.01
Stock options | Stock Incentive Plan
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices, Lower Range Limit	$ 14.86
Number of outstanding options, Range of Exercise Prices, Upper Range Limit	$ 60.56
Number of outstanding options, Shares	1,338,241
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	7.08
Stock options | Stock Incentive Plan | $14.86
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 14.86
Number of outstanding options, Shares	37,250
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	1.08
Stock options | Stock Incentive Plan | $21.38
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 21.38
Number of outstanding options, Shares	8,460
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	2.08
Stock options | Stock Incentive Plan | $46.45
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 46.45
Number of outstanding options, Shares	154,920
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	5.00
Stock options | Stock Incentive Plan | $55.08
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 55.08
Number of outstanding options, Shares	7,260
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	5.50
Stock options | Stock Incentive Plan | $60.56
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 60.56
Number of outstanding options, Shares	184,565
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	6.00
Stock options | Stock Incentive Plan | $29.79
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 29.79
Number of outstanding options, Shares	365,948
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	7.00
Stock options | Stock Incentive Plan | $43.30
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 43.30
Number of outstanding options, Shares	4,750
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	7.67
Stock options | Stock Incentive Plan | $46.69
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 46.69
Number of outstanding options, Shares	281,110
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	8.00
Stock options | Stock Incentive Plan | $54.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Range of Exercise Prices	$ 54.99
Number of outstanding options, Shares	293,978
Number of outstanding options, Weighted Average Remaining Contractual Life (in years)	9.00