Stock Compensation (Transactions of Stock Option Plan) (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted-average exercise price (in dollars per share)
Options granted (in dollars per share)	$ 23.08	$ 22.35
Omnibus Incentive Plan
Number of shares (in shares)
Beginning balance (in shares)	203,320	202,378	247,580
Options granted (in shares)	24,755	23,958	23,258
Options exercised (in shares)	(43,269)	(23,016)	(66,660)
Options forfeited (in shares)	0	0	(1,800)
Ending balance (in shares)	184,806	203,320	202,378
Weighted-average exercise price (in dollars per share)
Beginning balance (in dollars per share)	$ 41.80	$ 39.27	$ 34.26
Options granted (in dollars per share)	56.66	54.36	51.29
Options exercised (in dollars per share)	37.96	32.57	24.91
Options forfeited (in dollars per share)			37.78
Ending balance (in dollars per share)	$ 44.69	$ 41.80	$ 39.27
Exercisable options (in shares)	105,470	111,016	113,060
Exercisable options weighted average exercise price (in dollars per share)	$ 40.96	$ 39.68	$ 38.18
Omnibus Incentive Plan | Price range $24.94 — $36.59
Number of shares (in shares)
Ending balance (in shares)	59,500
Weighted-average exercise price (in dollars per share)
Ending balance (in dollars per share)	$ 35.87
Weighted average contractual life (in years)	5 years 9 months 18 days
Exercise price range - minimum (in dollars per share)	$ 24.94
Exercise price range - maximum (in dollars per share)	$ 36.59
Omnibus Incentive Plan | Price range $36.60 — $51.29
Number of shares (in shares)
Ending balance (in shares)	62,434
Weighted-average exercise price (in dollars per share)
Ending balance (in dollars per share)	$ 42.83
Weighted average contractual life (in years)	5 years
Exercise price range - minimum (in dollars per share)	$ 36.60
Exercise price range - maximum (in dollars per share)	$ 51.29
Omnibus Incentive Plan | Price range $51.30 — $56.66
Number of shares (in shares)
Ending balance (in shares)	62,872
Weighted-average exercise price (in dollars per share)
Ending balance (in dollars per share)	$ 54.89
Weighted average contractual life (in years)	3 years 6 months
Exercise price range - minimum (in dollars per share)	$ 51.30
Exercise price range - maximum (in dollars per share)	$ 56.66