Retirement Benefit Plans - Fair Value of U.S. and Puerto Rico Pension Plan Assets (Detail) - U.S. and Puerto Rico [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	$ 388.5	$ 433.6	$ 389.4
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	3.1	1.3
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	385.4	432.3
Cash and Cash Equivalents [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	3.1	1.3
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	3.1	1.3
Equity Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	231.7	287.1
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	231.7	287.1
Intermediate Fixed Income Debt Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Plan assets at fair market value	153.7	145.2
Intermediate Fixed Income Debt 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	$ 153.7	$ 145.2