Pension Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Defined Contribution Plan Disclosure [Line Items]
Defined contribution pension cost		$ 742	$ 580	$ 510
Percentage of capital and interest guaranteed by Swiss Life		100.00%
Accumulated pension obligation		$ 13,318	8,957	1,689
Plan assets		7,981	4,455
Net funded status		5,337	4,502
Accumulated pension obligation		13,318	8,957	$ 1,689
Contributions paid by plan participants		3,483	2,354
Contributions paid or to be paid by employer		$ 892	$ 487
Scenario, Forecast [Member]
Defined Contribution Plan Disclosure [Line Items]
Contributions paid or to be paid by employer	$ 986
Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Bond yield maturity period		15 years	15 years
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Bond yield maturity period		25 years	25 years
New Employees [Member]
Defined Contribution Plan Disclosure [Line Items]
Contributions paid by plan participants		$ 2,940	$ 2,058