Fair Value (Derivative Assets and Liabilities by Hierarchy) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	$ (1,660)	$ (81)
Fair Value, Measurements, Recurring | Level One
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	0
Fair Value, Measurements, Recurring | Level Two
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	(1,660)	(81)
Fair Value, Measurements, Recurring | Level Three
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	0
Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	(1,660)	(81)
Commodity Futures Natural Gas Contracts | Fair Value, Measurements, Recurring | Level One
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	0
Commodity Futures Natural Gas Contracts | Fair Value, Measurements, Recurring | Level Two
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	413	(420)
Commodity Futures Natural Gas Contracts | Fair Value, Measurements, Recurring | Level Three
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	0
Commodity Futures Natural Gas Contracts | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	413	(420)
Currency Contracts | Fair Value, Measurements, Recurring | Level One
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	0
Currency Contracts | Fair Value, Measurements, Recurring | Level Two
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	41
Currency Contracts | Fair Value, Measurements, Recurring | Level Three
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	0
Currency Contracts | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	41
Interest Rate Agreements | Fair Value, Measurements, Recurring | Level One
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	0
Interest Rate Agreements | Fair Value, Measurements, Recurring | Level Two
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	(2,073)	298
Interest Rate Agreements | Fair Value, Measurements, Recurring | Level Three
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	0	0
Interest Rate Agreements | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative asset (liability)	$ (2,073)	$ 298