Stock Option Plan and Stock Grants (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Number of Shares		Weighted Average Grant Date Fair Value
Balance at December 31, 2009	56,008		$	24.99
Shares granted	121,665		50.03
Share vested	(125,330	)	44.19
Balance at December 31, 2010	52,343		37.22
Shares granted	119,665		57.49
Shares canceled/forfeited	(11,333	)	57.40
Shares vested	(113,665	)	48.99
Balance at December 31, 2011	47,010		55.50
Shares granted	107,332		70.12
Shares canceled/forfeited	(18,333	)	70.14
Shares vested	(88,999	)	64.60
Balance at December 31, 2012	47,010		65.93

	Number of Shares		Weighted Average Grant Date Fair Value
Balance at December 31, 2009	56,008		$	24.99
Shares granted	121,665		50.03
Share vested	(125,330	)	44.19
Balance at December 31, 2010	52,343		37.22
Shares granted	119,665		57.49
Shares canceled/forfeited	(11,333	)	57.40
Shares vested	(113,665	)	48.99
Balance at December 31, 2011	47,010		55.50
Shares granted	107,332		70.12
Shares canceled/forfeited	(18,333	)	70.14
Shares vested	(88,999	)	64.60
Balance at December 31, 2012	47,010		65.93

Summary of Stock Option Activity

A summary of the Company’s stock option activity, and related information for the years ended December 31, 2012, 2011, and 2010 follows:

	Shares Subject To Options		Weighted Average Exercise Price Per Share		Weighted Average Outstanding Contractual Life (in years)
Balance at December 31, 2009	841,851		$	39.94	6.0
Options exercised	(33,767	)	32.77
Options canceled	(2,900	)	17.50
Balance at December 31, 2010	805,184		40.32		5.1
Options exercised	(172,384	)	26.28
Balance at December 31, 2011	632,800		44.14		5.0
Options exercised	(80,000	)	48.20
Balance at December 31, 2012	552,800		43.56		4.0
Exercisable at December 31, 2012	552,800		43.56		4.0