Income Taxes (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Income Taxes (Textual) [Abstract]
Income taxes paid	$ 36,783,000		$ 5,332,000		$ 36,269,000
Deferred tax assets	1,155,000		631,000
Deferred tax asset related to U.S. foreign tax credit	0		500,000
Valuation allowance amount			0
Deferred other tax expense	1,400,000
Accumulated other comprehensive loss	(54,595,000)	[1]	(21,181,000)	[1]	(45,379,000)	[1]
Amount from exercise of awards	0
Tax benefit realized from the exercise of awards	3,300,000		1,300,000.0
Interest and penalties accrued	400,000		200,000
Interest and penalties expense	200,000		100,000
State
Income Taxes (Textual) [Abstract]
Operating loss carryforwards with expiration date	12,100,000
Deferred tax assets	500,000
Operating loss carryforwards valuation allowance			100,000.0
Operating loss carryforwards			500,000
Municipal
Income Taxes (Textual) [Abstract]
Deferred tax assets	200,000
Operating loss carryforwards valuation allowance	200,000
Operating loss carryforwards	24,800,000
Canadian
Income Taxes (Textual) [Abstract]
Deferred tax assets	400,000
Operating loss carryforwards valuation allowance	0		0
Operating loss carryforwards	1,600,000
Deferred tax asset with respect to Canadian net operating loss carryforwards			100,000
Retiree Health Care Plan Liability and Medicare Part D Subsidy Error | Restatement Adjustment
Income Taxes (Textual) [Abstract]
Accumulated other comprehensive loss	$ 1,400,000

[1] All amounts are net of tax. Amounts in parentheses indicate debits