Employee Retirement Plans - Schedule of Estimated Amount that will be Amortized from Accumulated Other Comprehensive Loss into Net Periodic Benefit Cost in Next Fiscal Year (Detail) $ in Millions |
12 Months Ended |
|---|---|
|
Dec. 31, 2015
USD ($)
| |
| Pension Benefits [Member] | |
| Defined Benefit Plan Disclosure [Line Items] | |
| Actuarial loss | $ (2.8) |
| Total | (2.8) |
| OPEB Benefits [Member] | |
| Defined Benefit Plan Disclosure [Line Items] | |
| Prior service credit | 12.2 |
| Actuarial loss | (0.1) |
| Total | $ 12.1 |