Income Taxes - Components of Net Deferred Tax Liability (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Tax effect of temporary differences related to:
Inventories	$ 4.4	$ 3.6
Marketable securities
Accrued OPEB costs	4.6	6.9
Accrued pension costs	21.8	33.3
Accrued environmental liabilities	40.1	16.9
Other deductible differences	58.8	26.2
Tax loss and tax credit carryforwards	191.8	153.0
Valuation allowance	(0.1)	(0.2)
Adjusted gross deferred tax assets (liabilities)	321.4	239.7
Netting of items by tax jurisdiction, assets	(149.2)	(109.8)
Total	172.2	129.9
Less net current deferred tax asset (liability)	23.0	9.6
Net noncurrent deferred tax asset (liability)	149.2	120.3
Tax effect of temporary differences related to:
Inventories	(2.6)	(10.3)
Marketable securities	(145.8)	(164.8)
Property and equipment	(115.8)	(104.5)
Other taxable differences	(35.1)	(30.3)
Investments in subsidiaries and affiliates	(280.6)	(258.3)
Tax on unremitted earnings of non-U.S. subsidiaries	(2.6)	(7.6)
Adjusted gross deferred tax assets (liabilities)	(582.5)	(575.8)
Netting of items by tax jurisdiction, liabilities	(149.2)	(109.8)
Total	(433.3)	(466.0)
Less net current deferred tax asset (liability)	(2.2)	(11.2)
Net noncurrent deferred tax asset (liability)	$ (431.1)	$ (454.8)