Retirement Benefit Plans - Fair Value of Foreign Pension Plan Assets (Detail) - Foreign [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	$ 585.8	$ 574.9	$ 507.0
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	123.9	189.4
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	353.0	294.5
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	108.9	91.0
Cash and Cash Equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	14.6	31.8
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	14.6	31.8
Equity Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	138.6	161.6
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	109.3	157.6
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	29.3	4.0
Fixed Income Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	226.9	219.5
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	226.9	219.5
Other Types of Investments [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	96.8	60.4
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	96.8	60.4
Real Estate [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	108.9	101.6
Real Estate [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		10.6
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	$ 108.9	$ 91.0