Income Taxes - Schedule of Changes in Amount of Uncertain Tax Positions (Detail) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2015 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Unrecognized liabilities: | ||||
| Balance at the beginning of the period | $ 16.8 | $ 12.2 | $ 16.8 | $ 16.8 |
| Lapse of applicable statute of limitations | $ (3.0) | 0.0 | (4.6) | 0.0 |
| Balance at the end of the period | $ 12.2 | $ 12.2 | $ 16.8 | |