Employee Retirement Plans - Schedule of Projected Benefit Obligation and Fair Value of Plan Assets for Pension Plans Having Projected Benefit Obligations in Excess of Fair Value of Plan Assets (Detail) - Pension Benefits [Member] - USD ($) $ in Millions |
Dec. 31, 2015 |
Dec. 31, 2014 |
|---|---|---|
| Defined Benefit Plan Disclosure [Line Items] | ||
| Projected benefit obligation, end of year | $ 737.0 | $ 786.8 |
| Fair value of plan assets, end of year | $ 594.8 | $ 638.2 |