Income Taxes (Details Textual) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Tax Liability Expense [Line Items]
Effective tax rate	36.30%	37.90%	38.20%	37.40%
Deferred income taxes			$ 22,525,000	$ 4,399,000
Income Taxes Paid	3,300,000
Correction Of Other Comprehensive Income Related To Retiree Health Care Plan Liability And Medicare Part D Subsidy [Member]
Tax Liability Expense [Line Items]
Deferred income taxes			$ 1,400,000