Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Income Tax Disclosure [Abstract] | |||
| Beginning balance | $ 7.2 | $ 7.4 | $ 9.6 |
| Additions to tax positions related to the current period | 0.5 | 0.3 | 0.3 |
| Additions to tax positions related to the prior period | 0.2 | 0.4 | 0.3 |
| Reductions in tax positions resulting from settlements with taxing authorities | (3.5) | (1.3) | |
| Reductions in tax positions resulting from a lapse of the statute of limitations | (0.1) | (0.2) | |
| Other | (0.2) | (0.9) | (1.3) |
| Ending balance | $ 4.1 | $ 7.2 | $ 7.4 |