Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Mar. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	$ (28,310)		$ (28,310)			$ (26,128)
Intangible Assets, Net (Including Goodwill)	56,358		56,358			53,749
Finite-Lived Intangible Assets, Net	37,723		37,723			38,598
Finite-Lived Intangible Assets, Gross	66,033		66,033			64,726
Intangible Assets, Gross (Excluding Goodwill)	84,668		84,668			79,877
Indefinite-Lived Trademarks	15,356		15,356			15,151
Intangible Assets, Net (Excluding Goodwill)	56,358		56,358			53,749
Indefinite-lived Intangible Assets (Excluding Goodwill)	18,635		18,635			15,151
Goodwill	40,294		40,294			40,294
Amortization of Intangible Assets	1,200	$ 1,100	2,300	$ 2,300
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	4,900		4,900
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	13,400		13,400
Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	(12,847)		(12,847)			(12,046)
Finite-Lived Intangible Assets, Net	14,908		14,908			14,616
Finite-Lived Patents, Gross	27,755		27,755			26,662
Amortization of Intangible Assets	400	400	800	700
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	6,000		6,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	1,800		$ 1,800
Technology-Based Intangible Assets [Member] | Weighted Average [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life			15 years 3 months 18 days		15 years 9 months 18 days
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	(15,258)		$ (15,258)			(13,868)
Finite-Lived Intangible Assets, Net	22,815		22,815			23,982
Finite-Lived Customer Relationships, Gross	38,073		38,073			37,850
Amortization of Intangible Assets	800	$ 800	$ 1,500	$ 1,600
Finite-Lived Intangible Asset, Useful Life			12 years 2 months 12 days		12 years 3 months 18 days
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	7,400		$ 7,400
Finite-Lived Intangible Assets, Amortization Expense, Year Four	3,100		3,100
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	(205)		(205)			(214)
Finite-Lived Intangible Assets, Net	0		0			0
Other Finite-Lived Intangible Assets, Gross	205		205			214
Unclassified Indefinite-lived Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets (Excluding Goodwill)	3,279		3,279			0
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Net (Excluding Goodwill)	$ 15,356		$ 15,356			$ 15,151