Retirement Benefit Obligations - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2022 USD ($)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Company's contributions	$ 1.9
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Company's contributions	0.8
Supplemental Employee Retirement Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Benefit payments under SERP Plan	0.3
Expected additional benefit payments for the remainder of 2020	$ 0.3