Derivative Financial Instruments (Details 3) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	$ 1,372	$ 706
Gross amounts netted in the condensed consolidated balance sheet	(1,353)	(706)
Net amounts of liabilities presented in the condensed consolidated balance sheet	19	0
Amounts subject to master netting arrangements presented on a gross basis	0	0
Counterparty A | Current liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	17	157
Gross amounts netted in the condensed consolidated balance sheet	(17)	(157)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Amounts subject to master netting arrangements presented on a gross basis	0	0
Counterparty A | Other liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	0	0
Gross amounts netted in the condensed consolidated balance sheet	0	0
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Amounts subject to master netting arrangements presented on a gross basis	0	0
Counterparty B | Current liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	19	116
Gross amounts netted in the condensed consolidated balance sheet	(19)	(116)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Amounts subject to master netting arrangements presented on a gross basis	0	0
Counterparty B | Other liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	0	0
Gross amounts netted in the condensed consolidated balance sheet	0	0
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Amounts subject to master netting arrangements presented on a gross basis	0	0
Counterparty C | Current liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	950	368
Gross amounts netted in the condensed consolidated balance sheet	(950)	(368)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Amounts subject to master netting arrangements presented on a gross basis	0	0
Counterparty C | Other liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	378	0
Gross amounts netted in the condensed consolidated balance sheet	(359)	0
Net amounts of liabilities presented in the condensed consolidated balance sheet	19	0
Amounts subject to master netting arrangements presented on a gross basis	0	0
Counterparty D | Current liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	8	65
Gross amounts netted in the condensed consolidated balance sheet	(8)	(65)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Amounts subject to master netting arrangements presented on a gross basis	0	0
Counterparty D | Other liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	0	0
Gross amounts netted in the condensed consolidated balance sheet	0	0
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Amounts subject to master netting arrangements presented on a gross basis	$ 0	$ 0