Change in Fair Value of Contingent Consideration as Determined by Level 3 Inputs (Detail) - Contingent Consideration - ECP Entwicklungsgesellschaft mbH - Level 3 - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Level 3 liabilities, beginning balance	$ 9,153	$ 7,563	$ 6,510
Additions	0	0	0
Payments	0	0	0
Change in fair value	1,337	1,590	1,053
Level 3 liabilities, ending balance	$ 10,490	$ 9,153	$ 7,563