Goodwill and Intangibles - Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Sep. 30, 2019	Mar. 31, 2019
Schedule of Intangible Assets [Line Items]
Beginning Gross Carrying Amount	$ 165,910	$ 150,120
Additions	260	17,220
Accumulated Amortization	(63,494)	(59,793)
Impact of Foreign Currency Translation	324	(1,430)
Ending Intangible Assets, Net	103,000	106,117
Amortization of intangible assets	$ 3,701	$ 7,943
Customer relationships
Schedule of Intangible Assets [Line Items]
Weighted Average Remaining Useful Life	9 years 25 days	9 years 6 months 18 days
Beginning Gross Carrying Amount	$ 63,980	$ 58,530
Additions	0	5,450
Accumulated Amortization	(31,037)	(29,027)
Impact of Foreign Currency Translation	0	0
Ending Intangible Assets, Net	$ 32,943	$ 34,953
Production and supply contracts
Schedule of Intangible Assets [Line Items]
Weighted Average Remaining Useful Life	2 years 6 months	2 years 11 months 4 days
Beginning Gross Carrying Amount	$ 14,893	$ 14,893
Additions	0	0
Accumulated Amortization	(11,172)	(10,668)
Impact of Foreign Currency Translation	0	0
Ending Intangible Assets, Net	$ 3,721	$ 4,225
Internally developed software
Schedule of Intangible Assets [Line Items]
Weighted Average Remaining Useful Life	3 years 8 months 12 days	3 years 9 months 14 days
Beginning Gross Carrying Amount	$ 19,917	$ 18,812
Additions	189	1,105
Accumulated Amortization	(18,660)	(18,391)
Impact of Foreign Currency Translation	0	0
Ending Intangible Assets, Net	$ 1,446	$ 1,526
Licenses
Schedule of Intangible Assets [Line Items]
Weighted Average Remaining Useful Life	17 years 6 months	18 years 29 days
Beginning Gross Carrying Amount	$ 32,284	$ 30,339
Additions	71	2,991
Accumulated Amortization	(2,531)	(1,644)
Impact of Foreign Currency Translation	238	(1,046)
Ending Intangible Assets, Net	$ 30,062	$ 30,640
Trade names
Schedule of Intangible Assets [Line Items]
Weighted Average Remaining Useful Life	6 years 6 months	7 years
Beginning Gross Carrying Amount	$ 500	$ 0
Additions	0	500
Accumulated Amortization	(94)	(63)
Impact of Foreign Currency Translation	0	0
Ending Intangible Assets, Net	406	437
Goodwill
Schedule of Intangible Assets [Line Items]
Beginning Gross Carrying Amount	34,336	27,546
Additions	0	7,174
Impact of Foreign Currency Translation	86	(384)
Ending Intangible Assets, Net	$ 34,422	$ 34,336