Income Taxes - Components of Income Tax Expense (Benefit) From Operations (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Components Of Income Tax Expense Benefit Continuing Operations [Abstract] | |||
| U.S. Federal, Current | $ 28.6 | $ 41.3 | $ 34.2 |
| U.S. State and Local, Current | 9.0 | 12.1 | 10.5 |
| Foreign, Current | 3.5 | 3.8 | 3.2 |
| Current income tax expense | 41.1 | 57.2 | 47.9 |
| U.S. Federal, Deferred | (3.1) | 8.1 | (10.6) |
| U.S. State and Local, Deferred | (0.4) | 2.2 | (3.0) |
| Foreign, Deferred | (2.4) | (0.1) | 0.7 |
| Deferred income tax expense (benefit) | (5.9) | 10.2 | (12.9) |
| Total | $ 35.2 | $ 67.4 | $ 35.0 |