Employee Benefit Plans - Composition of Pension Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 491.7	$ 427.4
Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Plan assets	26.1	22.0
Quoted Prices in Active Markets (Level 1) | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	171.6	151.3
Quoted Prices in Active Markets (Level 1) | Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Plan assets	16.0	13.8
Significant Other Observable Inputs (Level 2) | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	46.5	45.6
Significant Unobservable Inputs (Level 3) | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	273.6	230.5	$ 236.2
Significant Unobservable Inputs (Level 3) | Other Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Plan assets	10.1	8.2
Germany | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	257.9	217.0
Germany | Significant Unobservable Inputs (Level 3) | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	257.9	217.0
Canada | Local Currency Equities | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	8.4	14.8
Canada | Foreign Equities | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	16.4	19.7
Canada | Local Currency Fixed Income | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	81.8	59.5
Canada | Cash and Other | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.3	0.4
Canada | Quoted Prices in Active Markets (Level 1) | Local Currency Equities | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	8.4	14.8
Canada | Quoted Prices in Active Markets (Level 1) | Foreign Equities | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	16.4	19.7
Canada | Quoted Prices in Active Markets (Level 1) | Local Currency Fixed Income | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	81.8	59.5
Canada | Quoted Prices in Active Markets (Level 1) | Cash and Other | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.3	0.4
Norway | Local Currency Equities | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1.8	1.6
Norway | Foreign Equities | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.6	4.1
Norway | Local Currency Fixed Income | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	21.0	23.2
Norway | Cash and Other | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	15.4	9.9
Norway | Foreign Fixed Income | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	6.8	5.4
Norway | Real Estate | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.7	4.2
Norway | Quoted Prices in Active Markets (Level 1) | Local Currency Equities | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1.8	1.6
Norway | Quoted Prices in Active Markets (Level 1) | Foreign Equities | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.6	4.1
Norway | Quoted Prices in Active Markets (Level 1) | Local Currency Fixed Income | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	21.0	23.2
Norway | Quoted Prices in Active Markets (Level 1) | Cash and Other | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	14.5	8.8
Norway | Quoted Prices in Active Markets (Level 1) | Foreign Fixed Income | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	6.8	5.4
Norway | Significant Unobservable Inputs (Level 3) | Cash and Other | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.9	1.1
Norway | Significant Unobservable Inputs (Level 3) | Real Estate | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.7	4.2
U.S. | CMRT | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	46.5	45.6
U.S. | Significant Other Observable Inputs (Level 2) | CMRT | Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 46.5	$ 45.6