Stock Compensation (Transactions of Stock Option Plan) (Details) (Omnibus Incentive Plan, USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options Outstanding, Beginning Balance (in shares)	245,090	251,250	264,010
Options granted (in shares)	45,100	31,500	36,000
Options exercised (in shares)	(37,450)	(33,180)	(48,760)
Options forfeited (in shares)	(5,160)	(4,480)
Options Outstanding, Ending Balance (in shares)	247,580	245,090	251,250
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options outstanding weighted average exercise price - Beginning Balance (in dollars per share)	$ 30.30	$ 26.59	$ 21.44
Per share fair value of options granted during the period (in dollars per share)	$ 36.15	$ 36.59	$ 38.41
Options exercised weighted average exercise price (in dollars per share)	$ 10.25	$ 7.07	$ 7.42
Options forfeited weighted average exercise price (in dollars per share)	$ 37.19	$ 38.20
Options outstanding weighted average exercise price - Ending Balance (in dollars per share)	$ 34.26	$ 30.30	$ 26.59
Exercisable options (in shares)	141,740	152,762	144,022
Exercisable options weighted average exercise price (in dollars per share)	$ 31.72	$ 25.29	$ 17.92
Price range $7.00 — $31.41
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options Outstanding, Ending Balance (in shares)	69,920
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options outstanding weighted average exercise price - Beginning Balance (in dollars per share)	$ 21.39
Weighted average contractual life (in years)	2 years 8 months 12 days
Exercise price range - minimum (in dollars per share)	$ 7.00
Exercise price range - maximum (in dollars per share)	$ 31.41
Price range $31.42 — $38.41
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options Outstanding, Ending Balance (in shares)	109,960
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options outstanding weighted average exercise price - Beginning Balance (in dollars per share)	$ 36.99
Weighted average contractual life (in years)	8 years 4 months 24 days
Exercise price range - minimum (in dollars per share)	$ 31.42
Exercise price range - maximum (in dollars per share)	$ 38.41
Price range $38.42 — $52.81
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options Outstanding, Ending Balance (in shares)	67,700
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options outstanding weighted average exercise price - Beginning Balance (in dollars per share)	$ 43.13
Weighted average contractual life (in years)	6 years
Exercise price range - minimum (in dollars per share)	$ 38.42
Exercise price range - maximum (in dollars per share)	$ 52.81