Goodwill and Intangibles Asset Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2015	Mar. 31, 2015	Mar. 31, 2014
Goodwill and Intangible Assets [Line Items]
Goodwill	$ 2,794	$ 2,794	$ 2,794	$ 2,794	$ 2,794	$ 2,794	$ 2,794
Gross balance							69,191
Amortizable Intangibles, Accumulated amortization							(34,466)
Finite-lived Intangible Assets [Roll Forward]
Net balance	30,994	31,891	34,235	34,725	31,891	33,550
Additions			126	269		303
Amortization expense	(896)	(897)	(811)	(759)		(1,962)
Net balance	30,098	30,994	33,550	34,235	30,098	31,891
North America [Member]
Goodwill and Intangible Assets [Line Items]
Goodwill	2,794				$ 2,794
Customer Relationships Intangible [Member]
Goodwill and Intangible Assets [Line Items]
Weighted average remaining useful life in years					9 years 6 months
Amortizable Intangibles, Gross carrying amount							33,700
Amortizable Intangibles, Accumulated amortization							(14,954)
Finite-lived Intangible Assets [Roll Forward]
Net balance	16,640	17,061	18,325	18,746	$ 17,061	17,903
Additions			0	0		0
Amortization expense	(421)	(421)	(422)	(421)		(842)
Net balance	16,219	16,640	17,903	18,325	$ 16,219	17,061
Production and Supply Contract Intangibles [Member]
Goodwill and Intangible Assets [Line Items]
Weighted average remaining useful life in years					5 years 3 months
Amortizable Intangibles, Gross carrying amount							14,893
Amortizable Intangibles, Accumulated amortization							(4,752)
Finite-lived Intangible Assets [Roll Forward]
Net balance	8,837	9,107	9,995	10,141	$ 9,107	9,808
Additions			0	0		0
Amortization expense	(272)	(270)	(187)	(146)		(701)
Net balance	8,565	8,837	9,808	9,995	$ 8,565	9,107
Internally Developed Software Intangible [Member]
Goodwill and Intangible Assets [Line Items]
Weighted average remaining useful life in years					0 years
Amortizable Intangibles, Gross carrying amount							17,804
Amortizable Intangibles, Accumulated amortization							$ (14,760)
Finite-lived Intangible Assets [Roll Forward]
Net balance	2,723	2,929	3,121	3,044	$ 2,929	3,045
Additions			126	269		303
Amortization expense	(203)	(206)	(202)	(192)		(419)
Net balance	$ 2,520	$ 2,723	$ 3,045	$ 3,121	$ 2,520	$ 2,929