Employee Benefits - Narrative (Detail)	1 Months Ended	6 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2020 USD ($)	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2022 USD ($) numberOfDerivativeInstruments investment age	Dec. 31, 2021 USD ($) numberOfDerivativeInstruments	Dec. 31, 2020 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Actuarial Loss (Gain)						$ (365,500,000)	$ (31,500,000)
Defined benefit plan, plan assets, period decrease						$ 532,100,000
Number of investments held in diversified portfolios | investment						1
Number of derivatives held by the plan | numberOfDerivativeInstruments						4	3
Expected long-term rate of return on assets						7.25%
Postretirement Health Care, minimum retirement age | age						55
Postretirement Health Care, minimum service term						15 years
Estimated contribution defined contribution plans						$ 67,200,000	$ 65,300,000	$ 62,900,000
Trust for Benefit of Employees
Defined Benefit Plan Disclosure [Line Items]
Assets related to the pension plan						$ 92,300,000	117,800,000
Long Credit Bonds
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						55.00%
Global Equities
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						15.00%
Custom Completion
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						10.00%
High Yield Bonds
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						4.00%
Northern Trust Private Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						5.00%
Northern Trust Private Equity Funds | Upper Limit
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						20.00%
Emerging Market Debt
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						3.00%
Global Listed Infrastructure
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						3.00%
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						3.00%
Northern Trust Hedge Fund
Defined Benefit Plan Disclosure [Line Items]
Target allocation of plan assets						2.00%
Supplemental Plan
Defined Benefit Plan Disclosure [Line Items]
Assets related to the pension plan						$ 0	0
Prior service costs, amortization period (years)						10 years
Defined benefit plan, net periodic benefit cost (credit), gain (loss) due to settlement						$ 0	0	0
Actuarial Loss (Gain)						(20,000,000.0)	(2,000,000.0)
Prior service (benefit) cost						$ 0	$ 100,000	200,000
Weighted average discount rate used in determining the accumulated postretirement benefit obligation						5.15%	2.80%
Other Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Prior service costs, amortization period (years)	13 years 10 months 24 days
Actuarial Loss (Gain)						$ 1,600,000	$ (3,300,000)
Prior service (benefit) cost	$ 12,700,000					$ (900,000)	$ (900,000)	(300,000)
Weighted average discount rate used in determining the accumulated postretirement benefit obligation						5.08%	2.56%
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Assets related to the pension plan						$ 1,176,800,000	$ 1,708,900,000
Contributions made to the pension plan						$ 20,700,000	6,700,000
Pension Plans, Defined Benefit | Lower Limit
Defined Benefit Plan Disclosure [Line Items]
Fair value, investments, entities that calculate net asset value per share, liquidating investment, remaining period						1 year
Pension Plans, Defined Benefit | Upper Limit
Defined Benefit Plan Disclosure [Line Items]
Fair value, investments, entities that calculate net asset value per share, liquidating investment, remaining period						15 years
Pension Plans, Defined Benefit | Northern Trust Private Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Assets related to the pension plan						$ 33,200,000	34,500,000
Pension Plans, Defined Benefit | Northern Trust Hedge Fund
Defined Benefit Plan Disclosure [Line Items]
Assets related to the pension plan						35,200,000	36,700,000
Pension Plans, Defined Benefit | Domestic Common Stock
Defined Benefit Plan Disclosure [Line Items]
Assets related to the pension plan						14,700,000	17,500,000
Pension Plans, Defined Benefit | Real Estate Funds
Defined Benefit Plan Disclosure [Line Items]
Assets related to the pension plan						$ 99,100,000	79,300,000
Fair value, investments, entities that calculate net asset value per share, investment redemption, notice period						45 days
U.S. | Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Assets related to the pension plan						$ 1,176,800,000	1,708,900,000	1,793,700,000
Contributions made to the pension plan						$ 0	0
Prior service costs, amortization period (years)						11 years
Defined benefit plan, net periodic benefit cost (credit), gain (loss) due to settlement						$ (44,100,000)	(27,900,000)	$ 0
Actuarial Loss (Gain)						(281,200,000)	(19,100,000)
Expected long-term rate of return on assets					5.00%			5.25%
Prior service (benefit) cost						$ (100,000)	$ (400,000)	$ (400,000)
Weighted average discount rate used in determining the accumulated postretirement benefit obligation						5.22%	3.03%
U.S. | Pension Plans, Defined Benefit | Lower Limit
Defined Benefit Plan Disclosure [Line Items]
Contribution to plan assets						$ 0
Expected long-term rate of return on assets		6.00%	5.25%	6.50%			5.25%	5.25%
U.S. | Pension Plans, Defined Benefit | Upper Limit
Defined Benefit Plan Disclosure [Line Items]
Contribution to plan assets						$ 561,000,000
Expected long-term rate of return on assets		6.00%		6.50%		5.25%