Employee Benefit Plans - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, employer contributions	$ 3,000,000	$ 0	$ 3,000,000	$ 0
Expected contribution to the plan during the remaining quarters of fiscal 2017			0
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, employer contributions	100,000		100,000	$ 0
Supplemental Executive Retirement Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to the plan during the remaining quarters of fiscal 2017			100,000
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Increase in net periodic benefit	$ 800,000		$ 1,700,000