Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Weighted Average Actuarial Assumptions Used to Develop Projected Benefit Obligation (Detail)

v3.6.0.2
Employee Benefit Plans - Weighted Average Actuarial Assumptions Used to Develop Projected Benefit Obligation (Detail) - Other Postretirement Benefit Plans [Member]
Mar. 31, 2016
Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]    
Discount rate 3.16% 3.11%
Medical care cost trend rate 8.00% 8.00%