Stock Option Accounting (Details) (USD $)	9 Months Ended
	Sep. 30, 2012
Summary of stock option activity
Outstanding at beginning of year, Amount	36,062
Exercised, Amount	(5,987)
Forfeited, Amount	(450)
Outstanding at end of period, Amount	29,625
Exercisable at end of period, Amount	29,625
Available to be granted at end of period, Amount	223,534
Outstanding at beginning of year, Weighted Average Exercise Price	$ 28.90
Exercised, Weighted Average Exercise Price	$ 22.87
Forfeited, Weighted Average Exercise Price	$ 22.50
Outstanding at end of period, Weighted Average Exercise Price	$ 30.22
Exercisable at end of period, Weighted Average Exercise Price	$ 30.22