Retirement Plans, Postretirement and Postemployment Benefits - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for defined benefit pension plans	$ 1,000.0	$ 974.0
Combined pension plan and SERP contributions	82.8	88.4
Estimated contribution of pension plans	93.5
Corporation's matching obligations	$ 20.5	$ 17.9	$ 17.6
Defined contribution plan name	401(a)
Postretirement Health Care Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated contribution of pension plans	$ 1.2