Income Taxes - Components of Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Restructuring reserves	$ 2.7	$ 6.6
Accruals not yet deductible for tax purposes	10.7	8.4
Net operating loss carryforwards	199.4	188.4
Foreign, federal and state credits	69.2	51.5
Employee benefit items	69.6	132.1
Capitalized expenses	10.8	45.7
Derivatives and other	23.7	0.0
Sub-total deferred tax assets	386.1	432.7
Valuation allowance	(189.2)	(167.7)
Total deferred tax assets	196.9	265.0
Depreciation and amortization	(13.9)	(24.7)
Unremitted foreign earnings	(9.0)	(22.2)
Intangibles	(26.3)	(23.6)
Other	0.0	(2.2)
Total deferred tax liabilities	(49.2)	(72.7)
Net deferred tax assets	$ 147.7	$ 192.3