Derivative Instruments and Hedging Activities (Potential Impact of Rights of Offset Associated with Recognized Assets and Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Offsetting Assets and Liabilities [Line Items]
Derivative Assets, Current	$ 0	$ 1,674
Current assets: Fair value of hedging contracts [Member] | Hedging Contracts [Member]
Offsetting Assets and Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	96
Derivative Asset, Collateral, Obligation to Return Cash, Offset	(96)
Derivative Asset, Fair Value, Amount Offset Against Collateral	0
Long-term assets: Fair value of hedging contracts [Member] | Hedging Contracts [Member]
Offsetting Assets and Liabilities [Line Items]
Derivative Asset, Fair Value, Gross Asset	155
Derivative Asset, Collateral, Obligation to Return Cash, Offset	(119)
Derivative Asset, Fair Value, Amount Offset Against Collateral	36
Current liabilities: Fair value of hedging contracts [Member] | Hedging Contracts [Member]
Offsetting Assets and Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	(1,235)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	96
Derivative Liability, Fair Value, Amount Offset Against Collateral	(1,139)
Long-term liabilities: Fair value of hedging contracts [Member] | Hedging Contracts [Member]
Offsetting Assets and Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability	(137)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	119
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ (18)