Stock Compensation (Nonvested Stock Roll Forward) (Details) (Restricted Stock, USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock
Shares
Beginning Balance	74,475	73,825	63,300
Granted	21,956	21,425	30,325
Vested	(24,350)	(16,875)	(17,900)
Forfeited	(3,625)	(3,900)	(1,900)
Ending Balance	68,456	74,475	73,825
Fair value per share (in dollars per share)
Beginning balance	$ 40.54	$ 37.01	$ 37.69
Granted	$ 54.36	$ 51.12	$ 36.15
Vested	$ 36.59	$ 38.41	$ 38.69
Forfeited	$ 41.61	$ 37.69	$ 21.77
Ending balance	$ 46.32	$ 40.54	$ 37.01
Unrecognized compensation cost	$ 1.3
Unrecognized compensation cost period (in years)	1 year 3 months 18 days