Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

Principal Components of Employee Benefit Costs

The principal components of employee benefit costs are summarized as follows:

	Year ended December 31,
	2023		2022			2021
	(in millions)
Expense:
Savings plan	$	34.5	$	37.3		$	73.7
Unfunded supplemental benefit plans		12.3		12.2			10.6
Other plans, net (1)		26.8		(14.7	)		24.4
	$	73.6	$	34.8		$	108.7

(1)For the year ended December 31, 2022, participant investments included in the deferred compensation plan realized losses in excess of expenses recorded by the Company.

Company's Benefit Obligations and Funded Status

The following table summarizes the benefit obligations and funded status associated with the Company’s unfunded supplemental benefit plans:

	December 31,
	2023			2022
	(in millions)
Change in projected benefit obligation:
Benefit obligation at beginning of year	$	196.4		$	262.1
Service costs		0.1			0.2
Interest costs		10.2			6.0
Actuarial loss (gain)		4.8			(57.4	)
Benefits paid		(15.5	)		(14.5	)
Projected benefit obligation at end of year		196.0			196.4
Change in plan assets:
Contributions		15.5			14.5
Benefits paid		(15.5	)		(14.5	)
Fair value of plan assets at end of year		—			—
Reconciliation of funded status:
Unfunded status of the plans	$	196.0		$	196.4
Amounts recognized in the consolidated balance sheet:
Accrued benefit liability	$	196.0		$	196.4
Amounts recognized in accumulated other         comprehensive income/loss:
Unrecognized net actuarial loss	$	50.9		$	48.1
	$	50.9		$	48.1
Accumulated benefit obligation at end of year	$	196.0		$	196.4

Net Periodic Benefit Costs

Net periodic benefit costs related to the Company’s unfunded supplemental benefit pension plans are summarized as follows:

	Year ended December 31,
	2023		2022		2021
	(in millions)
Expense:
Service costs	$	0.1	$	0.2	$	0.2
Interest costs		10.2		6.0		4.9
Amortization of net actuarial loss		2.0		5.8		6.8
Amortization of prior service cost (credit)		—		0.2		(1.3	)
	$	12.3	$	12.2	$	10.6

The Weighted-Average Discount Rate Assumptions Used to Determine Net Periodic Benefit Costs and Projected Benefit Obligations

The weighted-average discount rate assumptions used to determine net periodic benefit costs for the Executive and Management Supplemental Benefit Plans for the years ended December 31, 2023, 2022 and 2021, are as follows:

	Year ended December 31,
	2023			2022			2021
Discount rates:
Projected benefit obligation		5.56	%		2.89	%		2.49	%
Service cost		5.75	%		3.29	%		3.14	%
Interest cost		5.45	%		2.37	%		1.83	%

The weighted-average discount rate assumptions used to determine the projected benefit obligations for the Executive and Management Supplemental Benefit Plans at December 31, 2023 and 2022, are as follows:

	December 31,
	2023			2022
Discount rate		5.21	%		5.56	%

Benefit Payments

Benefit payments, which reflect expected future service, as appropriate, are expected to be made as follows:

Year	(in millions)
2024	$	16.2
2025	$	17.0
2026	$	16.7
2027	$	16.5
2028	$	16.2
Five years thereafter	$	74.8