Stock-Based Compensation (Details 1) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock option activity
Outstanding Options, Beginning Balance	145,069	222,446	249,515
Options Granted
Options Exercised	(23,189)	(57,027)	(1,483)
Options Canceled	(1,242)	(20,350)	(25,586)
Outstanding Options, Ending Balance	120,638	145,069	222,446
Options Vested	120,638
Options Exercisable	120,638
Weighted Average Exercise Price Per Share, Outstanding, Beginning Balance	$ 38.08	$ 33.20	$ 33.22
Weighted Average Exercise Price Per Share, Grants
Weighted Average Exercise Price Per Share, Exercised	$ 31.35	$ 27.94	$ 23.34
Weighted Average Exercise Price Per Share, Canceled	$ 20.00	$ 31.71	$ 34.41
Weighted Average Exercise Price Per Share, Outstanding, Ending Balance	$ 40.37	$ 38.08	$ 33.20
Weighted Average Exercise Price Per Share, Vested	$ 40.37
Weighted Average Exercise Price Per Share, Exercisable	$ 40.37
Weighted Average Remaining Contractual Life, Outstanding	1 year 6 months
Weighted Average Remaining Contractual Life, Vested	1 year 6 months
Weighted Average Remaining Contractual Life, Exercisable	1 year 6 months
Aggregate Intrinsic Value, Outstanding	$ 152,058
Aggregate Intrinsic Value, Vested	152,058
Aggregate Intrinsic Value, Exercisable	$ 152,058

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