Postretirement Benefits - Additional Information (Detail) $ in Millions	May 31, 2024 USD ($)
Schedule of Pension and Other Postretirement Benefits Expected Benefit Payments [Line Items]
Estimated benefits payable in the first year	$ 67.0
Estimated benefits payable in the second year	73.4
Estimated benefits payable in the third year	76.3
Estimated benefits payable in the fourth year	80.0
Estimated benefits payable in the fifth year	86.5
Estimated benefits payable in the years thereafter	432.5
Postretirement Benefits
Schedule of Pension and Other Postretirement Benefits Expected Benefit Payments [Line Items]
Estimated benefits payable in the years thereafter	8.1
Minimum | Postretirement Benefits
Schedule of Pension and Other Postretirement Benefits Expected Benefit Payments [Line Items]
Estimated benefits payable in the first year	1.1
Estimated benefits payable in the second year	1.1
Estimated benefits payable in the third year	1.1
Estimated benefits payable in the fourth year	1.1
Estimated benefits payable in the fifth year	1.1
Maximum | Postretirement Benefits
Schedule of Pension and Other Postretirement Benefits Expected Benefit Payments [Line Items]
Estimated benefits payable in the first year	1.4
Estimated benefits payable in the second year	1.4
Estimated benefits payable in the third year	1.4
Estimated benefits payable in the fourth year	1.4
Estimated benefits payable in the fifth year	$ 1.4