Commitments and Contingencies - Additional Information (Detail) £ in Thousands	12 Months Ended
	Mar. 31, 2017 USD ($) Contracts $ / £	Mar. 31, 2017 GBP (£)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2008 GBP (£)
Commitments And Contingencies [Line Items]
Expiry date of operating leases	2021	2021
Operating leases, Rent expense, Minimum rentals	$ 2,928,000		$ 2,923,000	$ 2,111,000
Capital Leased Assets, Gross Cost	1,928,000		2,098,000
Capital Leases, Balance Sheet, Assets by Major Class, Net	1,663,000		1,930,000
Research and development grant funding from Scottish Enterprise | £					£ 1,791
Claims from grant | £		£ 1,790
Total liabilities measured at fair value	252,000		190,000
Gain (loss) on foreign currency derivatives recorded in earnings, net	$ 0		$ 0	$ 0
Through June 2017 [Member]
Commitments And Contingencies [Line Items]
Number of forward exchange contracts | Contracts	3
Forward exchange contracts sold	$ 500,000
Forward exchange contracts exchange rate pounds sterling to US dollar | $ / £	1.40
July 2017 through September 2017 [Member]
Commitments And Contingencies [Line Items]
Number of forward exchange contracts | Contracts	3
Forward exchange contracts sold	$ 500,000
Forward exchange contracts exchange rate pounds sterling to US dollar | $ / £	1.2918
October 2017 through March 2018 [Member]
Commitments And Contingencies [Line Items]
Number of forward exchange contracts | Contracts	6
Forward exchange contracts sold	$ 500,000
Forward exchange contracts exchange rate pounds sterling to US dollar | $ / £	1.2655