Schedule of Offsetting Derivative Instruments by Type (Details) (Forward Contracts, USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Commodity Contracts
Derivative Asset, Fair Value, Net
Gross Amounts of Recognized Assets	$ 1,833	$ 514
Gross Amounts offset in the Statement of Financial Position	(155)	(211)
Net Amounts of Assets Presented in the Statement of Financial Position	1,678	303
Derivative, Collateral, Obligation to Return Securities	(1,678)	(281)
Cash Collateral Received	0	0
Derivative Asset, Net Amount	0	22
Derivative Liability, Fair Value, Net
Gross Amounts of Recognized Liabilities	2,550	492
Gross Amounts offset in the Statement of Financial Position	(155)	(211)
Net Amounts of Liabilities Presented in the Statement of Financial Position	2,395	281
Derivative, Collateral, Right to Reclaim Securities	(1,678)	(281)
Cash Collateral Pledged	0	0
Derivative Liability, Net Amount	717	0
Fair Value Hedges
Derivative Liability, Fair Value, Net
Gross Amounts of Recognized Liabilities	878	2,304
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Liabilities Presented in the Statement of Financial Position	878	2,304
Derivative, Collateral, Right to Reclaim Securities	0	0
Cash Collateral Pledged	0	0
Derivative Liability, Net Amount	$ 878	$ 2,304