Stock-Based Compensation (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number Of Stock Options Settled For Fully Vested Shares	782,980
Number Of Shares Issued In Settlement Of Stock Option	214,624
Deferred Income Tax Expense (Benefit)	$ 716,000	$ 147,000	$ 935,000
Unrecognised Compensation Cost	1,317,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	2 years 10 months 24 days
Proceeds from stock option exercises	284,000	355,000	39,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	6,544,000	123,000	130,000
Adjustments To Additional Paid In Capital, Income Tax Benefit From Share-Based Compensation	2,034,000
Shares Representing Outstanding Award	583,692
Restricted Stock Units (Rsus) [Member]
Unrecognised Compensation Cost	3,326,000
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	4 years 6 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value	1,667,000	1,024,000	1,071,000
Stock Option [Member]
Deferred Income Tax Expense (Benefit)	571,000	645,000	551,000
Adjustments To Additional Paid In Capital, Income Tax Benefit From Share-Based Compensation	$ 2,034,000	$ 131,000	$ 129,000
Two Thousand and Eleven Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	1,355,764
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	252,000
Common Stock, Capital Shares Reserved for Future Issuance	1,147,780