Defined Benefit Pension Plans - Costs of Defined Benefit Pension Plan (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Employer service cost	$ 337	$ 120	$ 1,022	$ 360
Interest cost	10	6	30	18
Expected return on plan assets	(15)	(6)	(46)	(18)
Amortization of actuarial (gains) losses	42		129
Net pension cost for the year	$ 374	$ 120	$ 1,135	$ 360