Income Taxes (Details Textual) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Tax Liability Expense [Line Items]
Effective tax rate	36.50%	37.60%	37.70%	37.40%
Deferred income taxes			$ 24,185,000	$ 6,893,000
Correction Of Other Comprehensive Income Related To Retiree Health Care Plan Liability And Medicare Part D Subsidy [Member]
Tax Liability Expense [Line Items]
Other Comprehensive Income (Loss), Tax			1,400,000
Deferred income taxes			$ 1,400,000