Schedule I - Condensed Financial Information of the Parent (Condensed Statements of Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Other, net					$ 1,225	$ 277	$ 456
Other (income) expense					7,028	10,264	5,616
Administrative and general expenses					193,925	198,697	199,331
Loss before income taxes					24,799	(76,573)	55,720
Income tax benefit					2,815	(38,455)	11,270
Net income (loss)	$ 18,091	$ 3,141	$ (275)	$ 1,027	21,984	(38,118)	44,450
Foreign currency translation adjustment					(2,756)	(1,896)	(229)
Deferred gain on available for sale securities, net of tax					17	442	729
Current period cash flow hedging activity, net of $357 tax benefit in 2015, $838 tax benefit in 2014 and $477 tax expense in 2013					(577)	(1,518)	810
Reclassification of hedging activities into earnings, net of $191 tax benefit in 2015, $489 tax benefit in 2014 and $95 tax benefit in 2013					409	898	152
Current period pension and postretirement plan adjustment, net of $1,222 tax benefit in 2015, $3,292 tax benefit in 2014 and $5,531 tax expense in 2013					(1,204)	(6,483)	8,022
Curtailment gain into earnings, net of $718 tax expense in 2013					0	0	(983)
Reclassification of pension and postretirement adjustments into earnings, net of $420 tax benefit in 2015, $313 tax benefit in 2014 and $740 tax benefit in 2013					856	627	1,101
Total other comprehensive income (loss)					(3,255)	(7,930)	9,602
Comprehensive income (loss)					18,729	(46,048)	54,052
Derivatives qualifying as hedges tax expense (benefit)					(357)	(838)	477
Reclassification adjustment from AOCI on derivatives tax expense (benefit)					191	489	95
Pension and other postretirement benefit plans tax expense (benefit)					1,222	3,292	(5,531)
Finalization of pension and non pension postretirement plan valuation tax expense					0	0	718
Amortization adjustment from AOCI pension and other post retirement plans, tax expense (benefit)					(420)	(313)	(740)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Intercompany interest expense					1,309	1,305	1,431
Other, net					(270)	(276)	(471)
Other (income) expense					1,039	1,029	960
Administrative and general expenses					3,704	4,862	5,670
Loss before income taxes					(4,743)	(5,891)	(6,630)
Income tax benefit					(1,496)	(1,764)	(1,527)
Net loss before equity in earnings of subsidiaries					(3,247)	(4,127)	(5,103)
Equity in earnings of subsidiaries					25,231	(33,991)	49,553
Net income (loss)					21,984	(38,118)	44,450
Foreign currency translation adjustment					(2,756)	(1,896)	(229)
Deferred gain on available for sale securities, net of tax					17	442	729
Current period cash flow hedging activity, net of $357 tax benefit in 2015, $838 tax benefit in 2014 and $477 tax expense in 2013					(577)	(1,518)	810
Reclassification of hedging activities into earnings, net of $191 tax benefit in 2015, $489 tax benefit in 2014 and $95 tax benefit in 2013					409	898	152
Current period pension and postretirement plan adjustment, net of $1,222 tax benefit in 2015, $3,292 tax benefit in 2014 and $5,531 tax expense in 2013					(1,204)	(6,483)	8,022
Curtailment gain into earnings, net of $718 tax expense in 2013					0	0	(983)
Reclassification of pension and postretirement adjustments into earnings, net of $420 tax benefit in 2015, $313 tax benefit in 2014 and $740 tax benefit in 2013					856	627	1,101
Total other comprehensive income (loss)					(3,255)	(7,930)	9,602
Comprehensive income (loss)					18,729	(46,048)	54,052
Derivatives qualifying as hedges tax expense (benefit)					(357)	(838)	477
Reclassification adjustment from AOCI on derivatives tax expense (benefit)					(191)	(489)	(95)
Pension and other postretirement benefit plans tax expense (benefit)					(1,222)	(3,292)	5,531
Finalization of pension and non pension postretirement plan valuation tax expense					0	0	718
Amortization adjustment from AOCI pension and other post retirement plans, tax expense (benefit)					$ (420)	$ (313)	$ (740)