Defined Contribution and Defined Benefit Retirement - Composition of Pension Plan Assets (Detail) - Defined Benefit Pension Plans - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 548.2	$ 498.4
Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	204.9	191.6
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	10.1	8.7
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	314.8	283.5	$ 259.6
Assets measured at NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets	18.4	14.6
Non U.S.
Defined Benefit Plan Disclosure [Line Items]
Plan assets	494.8	450.0	410.7
Germany
Defined Benefit Plan Disclosure [Line Items]
Plan assets	292.5	264.5
Germany | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	292.5	264.5
Canada | Local Currency Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.2	8.3
Canada | Non Local Currency Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	26.6	16.3
Canada | Local Currency Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	87.3	80.9
Canada | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.9	0.6
Canada | Quoted Prices in Active Markets (Level 1) | Local Currency Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.2	8.3
Canada | Quoted Prices in Active Markets (Level 1) | Non Local Currency Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	26.6	16.3
Canada | Quoted Prices in Active Markets (Level 1) | Local Currency Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	87.3	80.9
Canada | Quoted Prices in Active Markets (Level 1) | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.9	0.6
Norway | Local Currency Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	3.2	1.6
Norway | Non Local Currency Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	6.3	4.2
Norway | Local Currency Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	26.4	22.8
Norway | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	5.5	8.2
Norway | Non Local Currency Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	7.7	8.3
Norway | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	7.1	6.6
Norway | Quoted Prices in Active Markets (Level 1) | Local Currency Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	3.2	1.6
Norway | Quoted Prices in Active Markets (Level 1) | Non Local Currency Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	6.3	4.2
Norway | Quoted Prices in Active Markets (Level 1) | Local Currency Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	16.3	14.1
Norway | Quoted Prices in Active Markets (Level 1) | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.8	7.4
Norway | Quoted Prices in Active Markets (Level 1) | Non Local Currency Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	7.7	8.3
Norway | Significant Other Observable Inputs (Level 2) | Local Currency Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	10.1	8.7
Norway | Significant Unobservable Inputs (Level 3) | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.7	0.8
Norway | Significant Unobservable Inputs (Level 3) | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Plan assets	7.1	6.6
Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	31.1	27.6
Other | Quoted Prices in Active Markets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	17.3	16.6
Other | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	13.8	11.0
U.S.
Defined Benefit Plan Disclosure [Line Items]
Plan assets	53.3	48.4	$ 43.2
U.S. | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	5.7	6.0
U.S. | Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	20.9	19.2
U.S. | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	26.8	23.3
U.S. | Quoted Prices in Active Markets (Level 1) | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	4.4	4.6
U.S. | Quoted Prices in Active Markets (Level 1) | Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	3.1	5.4
U.S. | Quoted Prices in Active Markets (Level 1) | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets	26.8	23.3
U.S. | Significant Unobservable Inputs (Level 3) | Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.7	0.6
U.S. | Assets measured at NAV | Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1.3	1.4
U.S. | Assets measured at NAV | Equities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 17.1	$ 13.2