Retirement Benefit Plans - Fair Value of Foreign Pension Plan Assets (Detail) - Foreign [Member] - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	$ 665.2	$ 585.8	$ 574.9
Fair Value Measurements at Reporting Date Using: Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	147.8	123.9
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	393.7	353.0
Fair Value Measurements at Reporting Date Using: Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	123.7	108.9
Cash and Cash Equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	31.8	14.6
Cash and Cash Equivalents [Member] | Fair Value Measurements at Reporting Date Using: Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	31.8	14.6
Equity Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	140.9	138.6
Equity Securities [Member] | Fair Value Measurements at Reporting Date Using: Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	116.0	109.3
Equity Securities [Member] | Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	24.9	29.3
Fixed Income Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	245.2	226.9
Fixed Income Securities [Member] | Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	245.2	226.9
Other Types of Investments [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	123.6	96.8
Other Types of Investments [Member] | Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	123.6	96.8
Real Estate [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	123.7	108.9
Real Estate [Member] | Fair Value Measurements at Reporting Date Using: Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	$ 123.7	$ 108.9