Stock Compensation (Nonvested Stock Roll Forward) (Details) - Restricted Stock - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares
Beginning Balance (in shares)	68,456	74,475	73,825
Granted (in shares)	19,193	21,956	21,425
Vested (in shares)	(26,075)	(24,350)	(16,875)
Forfeited (in shares)	(1,450)	(3,625)	(3,900)
Ending Balance (in shares)	60,124	68,456	74,475
Fair value per share (in dollars per share)
Beginning balance (in dollars per share)	$ 46.32	$ 40.54	$ 37.01
Granted (in dollars per share)	56.66	54.36	51.12
Vested (in dollars per share)	36.15	36.59	38.41
Forfeited (in dollars per share)	48.87	41.61	37.69
Ending balance (in dollars per share)	$ 53.97	$ 46.32	$ 40.54
Unrecognized compensation cost	$ 1.2
Unrecognized compensation cost period (in years)	1 year 2 months 12 days