Derivative Financial Instruments (Details 3) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	$ 4,018	$ 10,649
Gross amounts netted in the consolidated balance sheet	(4,009)	(7,704)
Net amounts of liabilities presented in the condensed consolidated balance sheet	9	2,945
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty A [Member] | Other Current Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	534	2,550
Gross amounts netted in the consolidated balance sheet	(534)	(1,746)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	804
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty A [Member] | Other Noncurrent Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	243	0
Gross amounts netted in the consolidated balance sheet	(243)	0
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty B [Member] | Other Current Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	556	2,136
Gross amounts netted in the consolidated balance sheet	(556)	(1,371)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	765
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty B [Member] | Other Noncurrent Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	233	668
Gross amounts netted in the consolidated balance sheet	(233)	(668)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty C [Member] | Other Current Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	1,568	3,996
Gross amounts netted in the consolidated balance sheet	(1,568)	(2,873)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	1,123
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty C [Member] | Other Noncurrent Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	629	1,299
Gross amounts netted in the consolidated balance sheet	(620)	(1,046)
Net amounts of liabilities presented in the condensed consolidated balance sheet	9	253
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty D [Member] | Other Current Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	8	0
Gross amounts netted in the consolidated balance sheet	(8)	0
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty D [Member] | Other Noncurrent Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	0	0
Gross amounts netted in the consolidated balance sheet	0	0
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0	0
Counterparty E [Member] | Other Current Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	165
Gross amounts netted in the consolidated balance sheet	(165)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	0
Counterparty E [Member] | Other Noncurrent Liabilities [Member]
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	82
Gross amounts netted in the consolidated balance sheet	(82)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0
Derivative Asset, Fair Value, Subject to Master Netting, Gross Asset Basis	$ 0