Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Sep. 30, 2020	Mar. 31, 2020
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,104	$ 3,945
Accumulated Amortization	(3,490)	(3,320)
Net Carrying Amount	$ 614	$ 625
Weighted Average Remaining Useful Life	16 years 8 months 12 days	16 years 6 months
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2,534	$ 2,436
Accumulated Amortization	(2,534)	(2,436)
Brands Associated with Acquired Cell Lines [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	523	502
Accumulated Amortization	(171)	(158)
Net Carrying Amount	$ 352	$ 344
Weighted Average Remaining Useful Life	26 years 10 months 24 days	27 years 4 months 24 days
Product Licenses [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 882	$ 849
Accumulated Amortization	(620)	(568)
Net Carrying Amount	$ 262	$ 281
Weighted Average Remaining Useful Life	3 years	3 years 3 months 18 days
Other Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 165	$ 158
Accumulated Amortization	$ (165)	$ (158)