Accounting for Stock-Based Compensation (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2012
Stock options outstanding
Range of Exercise Prices, Minimum	$ 7.01
Range of Exercise Prices, Maximum	$ 26.00
Options Outstanding, Number	638,800
Options Outstanding, Weighted Average Remaining Contractual Term	7 years 3 months 4 days
Options Outstanding, Weighted Average Exercise Price	$ 22.21
Options Exercisable, Number	293,896
Options Exercisable, Weighted Average Exercise Price	$ 19.92
Range One [Member]
Stock options outstanding
Range of Exercise Prices, Minimum	$ 7.01
Range of Exercise Prices, Maximum	$ 10.00
Options Outstanding, Number	27,500
Options Outstanding, Weighted Average Remaining Contractual Term	2 years 6 months 11 days
Options Outstanding, Weighted Average Exercise Price	$ 8.24
Options Exercisable, Number	27,500
Options Exercisable, Weighted Average Exercise Price	$ 8.24
Range Two [Member]
Stock options outstanding
Range of Exercise Prices, Minimum	$ 18.01
Range of Exercise Prices, Maximum	$ 23.00
Options Outstanding, Number	305,749
Options Outstanding, Weighted Average Remaining Contractual Term	6 years 7 months 13 days
Options Outstanding, Weighted Average Exercise Price	$ 20.37
Options Exercisable, Number	181,368
Options Exercisable, Weighted Average Exercise Price	$ 19.39
Range Three [Member]
Stock options outstanding
Range of Exercise Prices, Minimum	$ 23.01
Range of Exercise Prices, Maximum	$ 26.00
Options Outstanding, Number	305,551
Options Outstanding, Weighted Average Remaining Contractual Term	8 years 3 months 26 days
Options Outstanding, Weighted Average Exercise Price	$ 25.32
Options Exercisable, Number	85,028
Options Exercisable, Weighted Average Exercise Price	$ 24.84