Long-Term Debt - Aggregate Maturities of Long-Term Debt and Other (Detail) - USD ($) $ in Millions |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Long Term Debt By Maturity [Abstract] | ||
| 2017 | $ 3.6 | |
| 2018 | 4.1 | |
| 2019 | 4.2 | |
| 2020 | 330.6 | |
| 2021 | 0.7 | |
| 2022 and thereafter | 0.3 | |
| Gross maturities | 343.5 | |
| Less original issue discount and debt issuance costs | 4.5 | |
| Total debt | $ 339.0 | $ 341.0 |