Stock Options - Information regarding stock option activity (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share Based Compensation, Shares Authorized Under Stock Option Plans, Exercise Price Range, Number Of Outstanding Options [Roll Forward]
Balances	177,641	208,643	224,782
Additional options authorized	250,000
Granted
Exercised	(15,095)	(31,002)	(14,529)
Forfeited or expired			(1,600)
Balances	412,546	177,641	208,643
Share Based Compensation, Shares Authorized Under Stock Option Plans, Exercise Price Range, Outstanding Shares [Roll Forward]
Balances	167,983	175,485	174,220
Granted	21,000	23,500	23,404
Exercised	(15,095)	(31,002)	(14,539)
Forfeited or expired			(7,600)
Balances	173,888	167,983	175,485
Share Based Compensation, Shares Authorized Under Stock Option Plans, Exercise Price Range, Weighted Average Exercise Price [Roll Forward]
Balances	$ 12.53	$ 11.39	$ 11.20
Granted	$ 11.03	$ 13.46	$ 7.52
Exercised	$ 8.83	$ 6.65	$ 3.17
Forfeited or expired			$ 10.31
Balances	$ 13.39	$ 12.53	$ 11.39
Share Based Compensation, Shares Authorized Under Stock Option Plans, Exercise Price Range, Lower Range Limit [Roll Forward]
Balances	$ 1.75	$ 1.75	$ 4.60
Granted	$ 16.77	$ 12.96	$ 7.50
Exercised	$ 2.90	$ 1.75	$ 2.70
Forfeited or expired			$ 2.90
Balances	$ 2.70	$ 1.75	$ 1.75
Share Based Compensation, Shares Authorized Under Stock Option Plans, Exercise Price Range, Upper Range Limit [Roll Forward]
Balances	$ 30.55	$ 30.55	$ 30.55
Granted	$ 1,822.00	$ 16.33	$ 7.63
Exercised	$ 11.05	$ 13.80	$ 7.50
Forfeited or expired			$ 11.25
Balances	$ 30.55	$ 30.55	$ 30.55