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Components of Company's Net Pension Expense (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Pension and Other Postretirement Benefits Disclosure [Line Items] |  |  |
Total recognized in other comprehensive loss | $ (12.1) | $ 9.0 | $ (1.0)
Pension Plans, Defined Benefit |  |  |
Pension and Other Postretirement Benefits Disclosure [Line Items] |  |  |
Service cost | 1.8 | 1.8 | 1.9
Interest cost | 30.0 | 30.6 | 37.6
Expected return on plan assets | (58.4) | (55.9) | (57.5)
Net actuarial loss (gain) | 17.9 | 17.7 | 19.1
Prior service cost | (0.4) | (1.1) | (1.0)
Curtailment and other one-time charges | 0.0 | 0.0 | 0.0
Defined-benefit plan (income) cost | (9.1) | (6.9) | 0.1
Various U.S. defined contribution plans cost | 12.0 | 11.6 | 10.8
Defined Benefit Plan And Defined Contribution Plan Periodic Benefit Cost, Total | 2.9 | 4.7 | 10.9
Other changes in plan assets and projected benefit obligation recognized in other comprehensive loss Net actuarial (gain) loss | (3.8) | 29.9 | 17.2
Amortization of net actuarial (loss) gain | (17.9) | (17.7) | (19.1)
Prior service cost |  | 0.6 | 2.5
Amortization of prior service cost | 0.5 | 1.1 | 1.0
Total recognized in other comprehensive loss | (21.2) | 13.9 | 1.6
Total recognized in net periodic (benefit) cost and other comprehensive loss | (30.3) | 7.0 | 1.7
Post-Retirement Benefits |  |  |
Pension and Other Postretirement Benefits Disclosure [Line Items] |  |  |
Service cost | 0.1 | 0.1 | 0.1
Interest cost | 0.3 | 0.2 | 0.3
Net actuarial loss (gain) | (0.1) | (0.2) | (0.1)
Prior service cost | (0.4) | (0.4) | (0.4)
Curtailment and other one-time charges | 0.0 | 0.0 | 0.0
Defined-benefit plan (income) cost | (0.1) | (0.3) | (0.1)
Other changes in plan assets and projected benefit obligation recognized in other comprehensive loss Net actuarial (gain) loss | 1.1 | 0.2 |
Amortization of net actuarial (loss) gain | 0.1 | 0.2 | 0.1
Prior service cost |  |  | (3.7)
Amortization of prior service cost | 0.4 | 0.4 | 0.4
Total recognized in other comprehensive loss | 1.6 | 0.8 | (3.2)
Total recognized in net periodic (benefit) cost and other comprehensive loss | $ 1.5 | $ 0.5 | $ (3.3)

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