Derivative Contracts (Details 2) (Not Designated as Hedging Instrument [Member], Forward Contracts, USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Contract value	$ 2,146	$ 908
Fair value	2,160	944
Derivative, Gain (Loss) on Derivative, Net	14	36
0 to 30
Derivative [Line Items]
Contract value	0	750
Fair value	0	780
Derivative, Gain (Loss) on Derivative, Net	0	30
Contract days until maturity, lower range	0 days	0 days
Contract days until maturity, higher range	30 days	30 days
31 to 60
Derivative [Line Items]
Contract value	28	90
Fair value	30	93
Derivative, Gain (Loss) on Derivative, Net	2	3
Contract days until maturity, lower range	31 days	31 days
Contract days until maturity, higher range	60 days	60 days
61 to 90
Derivative [Line Items]
Contract value	792	0
Fair value	797	0
Derivative, Gain (Loss) on Derivative, Net	5	0
Contract days until maturity, lower range	61 days	61 days
Contract days until maturity, higher range	90 days	90 days
91 to 120
Derivative [Line Items]
Contract value	893	68
Fair value	898	71
Derivative, Gain (Loss) on Derivative, Net	5	3
Contract days until maturity, lower range	91 days	91 days
Contract days until maturity, higher range	120 days	120 days
121 to 180
Derivative [Line Items]
Contract value		0
Fair value		0
Derivative, Gain (Loss) on Derivative, Net		0
Contract days until maturity, lower range		121 days
Contract days until maturity, higher range		180 days
More than 120
Derivative [Line Items]
Contract value	433
Fair value	435
Derivative, Gain (Loss) on Derivative, Net	2
Contract days until maturity, higher range	120 days
More than 180
Derivative [Line Items]
Contract value		0
Fair value		0
Derivative, Gain (Loss) on Derivative, Net		$ 0
Contract days until maturity, higher range		180 days