Derivatives (Fair Value of Derivative Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Fair value, derivative asset	$ 185	$ 339
Fair value, derivative liability	1,829	420
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value, derivative asset	0	298
Fair value, derivative liability	1,667	420
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair value, derivative asset	185	41
Fair value, derivative liability	162	0
Interest rate agreements [Member] | Designated as Hedging Instrument [Member] | Derivative Asset [Member]
Derivatives, Fair Value [Line Items]
Fair value, derivative asset	0	298
Interest rate agreements [Member] | Designated as Hedging Instrument [Member] | Other Long-Term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value, derivative liability	1,451	0
Interest rate agreements [Member] | Not Designated as Hedging Instrument [Member] | Other Long-Term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value, derivative liability	162	0
Natural gas contracts [Member] | Designated as Hedging Instrument [Member] | Derivative Liability, Current [Member]
Derivatives, Fair Value [Line Items]
Fair value, derivative liability	193	420
Natural gas contracts [Member] | Designated as Hedging Instrument [Member] | Other Long-Term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value, derivative liability	23	0
Currency contracts [Member] | Not Designated as Hedging Instrument [Member] | Prepaid and other current assets [Member]
Derivatives, Fair Value [Line Items]
Fair value, derivative asset	$ 185	$ 41