Defined Benefit Plans - Fair Value of Pension Assets by Major Category of Plan Assets (Detail) - USD ($) $ in Millions |
Dec. 31, 2017 |
Dec. 31, 2016 |
---|---|---|
Defined Benefit Plan Disclosure [Line Items] | ||
Fair value of pension assets | $ 656.6 | $ 577.7 |
Group annuity/insurance contracts (Level 3) | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Fair value of pension assets | 23.3 | 22.8 |
Cash and cash equivalents | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Fair value of pension assets | 12.5 | 6.9 |
Equity | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Fair value of pension assets | 285.9 | 258.8 |
Fixed income | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Fair value of pension assets | 277.7 | 235.4 |
Multi-strategy hedge funds | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Fair value of pension assets | 24.6 | 23.1 |
Real estate [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Fair value of pension assets | $ 32.6 | $ 30.7 |