Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Change In Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	$ 1,037.9
Employer contributions	82.8	$ 88.4
Balance at end of year	1,200.3	1,037.9
Pension
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	1,037.9	868.0
Actual return on plan assets, net	121.7	127.7
Employer contributions	82.8	88.4
Gross benefits paid	(42.1)	(46.2)
Balance at end of year	1,200.3	1,037.9
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	0.9	1.3
Participants' contributions	0.6	0.7
Gross benefits paid	$ (1.5)	$ (2.0)