Employee and Agent Benefits (Tables)

12 Months Ended

Dec. 31, 2023

Defined Benefit Plans and Other Postretirement Benefit Plans

Obligations and Funded Status (Table)

					Other postretirement
	Pension benefits				benefits
	December 31,				December 31,
	2023		2022		2023		2022
	(in millions)
Change in benefit obligation
Benefit obligation at beginning of year	$	(3,209.4)	$	(4,183.7)	$	(71.0)	$	(95.3)
Service cost		(55.6)		(78.4)		—		—
Interest cost		(160.1)		(112.8)		(3.4)		(2.3)
Actuarial gain (loss)		(119.7)		1,023.5		(2.9)		19.5
Participant contributions		—		—		(6.1)		(6.4)
Benefits paid		153.9		142.0		15.0		13.5
Benefit obligation at end of year	$	(3,390.9)	$	(3,209.4)	$	(68.4)	$	(71.0)
Change in plan assets
Fair value of plan assets at beginning of year	$	2,726.3	$	3,550.1	$	94.4	$	119.8
Actual return on plan assets		258.5		(754.3)		12.7		(20.0)
Employer contribution		78.7		72.5		1.6		1.7
Participant contributions		—		—		6.1		6.4
Benefits paid		(153.9)		(142.0)		(15.0)		(13.5)
Fair value of plan assets at end of year	$	2,909.6	$	2,726.3	$	99.8	$	94.4
Amount recognized in statement of financial position
Other assets	$	—	$	—	$	31.4	$	23.4
Other liabilities		(481.3)		(483.1)		—		—
Total	$	(481.3)	$	(483.1)	$	31.4	$	23.4
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	$	425.4	$	442.0	$	(24.4)	$	(20.2)
Prior service benefit		(70.6)		(87.4)		(4.3)		(5.1)
Pre-tax accumulated other comprehensive (income) loss	$	354.8	$	354.6	$	(28.7)	$	(25.3)

Components of Net Periodic Benefit Cost (Income) (Table)

	Pension benefits						Other postretirement benefits
	For the year ended December 31,
	2023		2022		2021		2023		2022		2021
	(in millions)
Service cost	$	55.6	$	78.4	$	83.2	$	—	$	—	$	—
Interest cost		160.1		112.8		103.3		3.4		2.3		2.2
Expected return on plan assets		(163.2)		(178.9)		(182.7)		(4.6)		(4.9)		(4.8)
Amortization of prior service benefit		(16.8)		(16.8)		(16.8)		(0.8)		(1.1)		(1.1)
Recognized net actuarial (gain) loss		41.0		55.7		70.2		(1.0)		(1.1)		(0.5)
Net periodic benefit cost (income)	$	76.7	$	51.2	$	57.2	$	(3.0)	$	(4.8)	$	(4.2)

Amounts Recognized in Net Periodic Benefit Cost and Accumulated Other Comprehensive (Income) Loss (Table)

	Pension benefits				Other postretirement benefits
	For the year ended December 31,
	2023		2022		2023		2022
	(in millions)
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	$	24.4	$	(90.3)	$	(5.2)	$	5.4
Amortization of gain (loss)		(41.0)		(55.7)		1.0		1.1
Amortization of prior service benefit		16.8		16.8		0.8		1.1
Total recognized in pre-tax accumulated other comprehensive (income) loss	$	0.2	$	(129.2)	$	(3.4)	$	7.6
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	$	76.9	$	(78.0)	$	(6.4)	$	2.8

Weighted-Average Assumptions Used to Determine Benefit Obligations (Table)

	Pension benefits
	December 31,
	2023		2022
Discount rate	4.90	%	5.10	%
Interest crediting rate - cash balance benefit	5.00	%	5.00	%
Rate of compensation increase	4.56	%	4.53	%
	Other postretirement benefits
	December 31,
	2023		2022
Discount rate	4.80	%	5.00	%
Rate of compensation increase	N/A		N/A

Weighted-Average Assumptions Used to Determine Net Periodic Benefit Cost (Table)

	Pension benefits
	For the year ended December 31,
	2023		2022		2021
Discount rate	5.10	%	2.75	%	2.50	%
Expected long-term return on plan assets	6.20	%	5.20	%	5.55	%
Interest crediting rate - cash balance benefit	5.00	%	5.00	%	5.00	%
Rate of compensation increase:
Cash balance benefit	4.53	%	4.59	%	4.92	%
Traditional benefit	N/A	%	N/A	%	2.96	%
	Other postretirement benefits
	For the year ended December 31,
	2023		2022		2021
Discount rate	5.00	%	2.50	%	2.10	%
Expected long-term return on plan assets	5.05	%	4.25	%	4.25	%
Rate of compensation increase	N/A		N/A		N/A

Assumed Health Care Cost Trend Rates (Table)

	December 31,
	2023		2022
Health care cost trend rate assumed for next year under age 65	7.50	%	7.00	%
Health care cost trend rate assumed for next year age 65 and over	6.50	%	6.00	%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	4.50	%	4.50	%
Year that the rate reaches the ultimate trend rate (under age 65)	2032		2031
Year that the rate reaches the ultimate trend rate (65 and older)	2031		2028

Estimated Future Benefit Payments (Table)

			Other postretirement
			benefits (gross benefit
			payments, including
	Pension benefits		prescription drug benefits)
	(in millions)
Year ending December 31:
2024	$	207.8	$	13.0
2025		191.1		11.9
2026		204.2		10.6
2027		214.0		9.3
2028		218.9		8.5
2029-2033		1,212.7		33.8

Defined Benefit Pension Plans Supplemental Information (Table)

	For the year ended December 31,
	2023						2022
	Qualified		Nonqualified				Qualified		Nonqualified
	Plan		Plan		Total		Plan		Plan		Total
	(in millions)
Amount recognized in statement of financial position
Other assets	$	—	$	—	$	—	$	—	$	—	$	—
Other liabilities		(58.3)		(423.0)		(481.3)		(70.7)		(412.4)		(483.1)
Total	$	(58.3)	$	(423.0)	$	(481.3)	$	(70.7)	$	(412.4)	$	(483.1)
Amount recognized in accumulated other comprehensive loss
Total net actuarial loss	$	361.4	$	64.0	$	425.4	$	390.7	$	51.3	$	442.0
Prior service benefit		(60.0)		(10.6)		(70.6)		(72.6)		(14.8)		(87.4)
Pre-tax accumulated other comprehensive loss	$	301.4	$	53.4	$	354.8	$	318.1	$	36.5	$	354.6
Components of net periodic benefit cost
Service cost	$	51.6	$	4.0	$	55.6	$	72.5	$	5.9	$	78.4
Interest cost		139.7		20.4		160.1		98.7		14.1		112.8
Expected return on plan assets		(163.2)		—		(163.2)		(178.9)		—		(178.9)
Amortization of prior service benefit		(12.6)		(4.2)		(16.8)		(12.6)		(4.2)		(16.8)
Recognized net actuarial loss		38.8		2.2		41.0		39.7		16.0		55.7
Net periodic benefit cost	$	54.3	$	22.4	$	76.7	$	19.4	$	31.8	$	51.2
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	$	9.5	$	14.9	$	24.4	$	15.0	$	(105.3)	$	(90.3)
Amortization of net loss		(38.8)		(2.2)		(41.0)		(39.7)		(16.0)		(55.7)
Amortization of prior service benefit		12.6		4.2		16.8		12.6		4.2		16.8
Total recognized in pre-tax accumulated other comprehensive (income) loss	$	(16.7)	$	16.9	$	0.2	$	(12.1)	$	(117.1)	$	(129.2)
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	$	37.6	$	39.3	$	76.9	$	7.3	$	(85.3)	$	(78.0)

Pension benefits

Defined Benefit Plans and Other Postretirement Benefit Plans

Accumulated Benefit Obligation in Excess of Plan Assets (Table)

	December 31,
	2023		2022
	(in millions)
Projected benefit obligation	$	3,390.9	$	3,209.4
Accumulated benefit obligation		3,390.9		3,209.4
Fair value of plan assets		2,909.6		2,726.3

Fair Value of Plan Assets (Table)

	December 31, 2023
	Assets		Amount		Fair value hierarchy level
	measured at		measured at
	fair value		net asset value		Level 1		Level 2		Level 3
	(in millions)
Asset category
Pooled separate account investments:
U.S. large cap equity portfolios (1)	$	290.9	$	—	$	—	$	290.9	$	—
U.S. small/mid cap equity portfolios (2)		49.5		—		—		49.5		—
Balanced asset portfolios (3)		97.0		—		—		97.0		—
International equity portfolios (4)		141.8		—		—		141.8		—
Fixed income security portfolios (5)		27.9		—		—		27.9		—
Real estate investment portfolios (6)		204.1		—		—		204.1		—
Single client separate account investments:
Fixed income securities:
U.S. government and agencies		124.9		—		124.9		—		—
States and political subdivisions		27.0		—		—		27.0		—
Corporate		1,394.2		—		—		1,394.2		—
Pooled separate account investment (8)		497.9		—		—		497.9		—
Other (9)		54.4		—		—		54.4		—
Total	$	2,909.6	$	—	$	124.9	$	2,784.7	$	—

	December 31, 2022
	Assets		Amount		Fair value hierarchy level
	measured at		measured at
	fair value		net asset value		Level 1		Level 2		Level 3
	(in millions)
Asset category
Pooled separate account investments:
U.S. large cap equity portfolios (1)	$	282.5	$	—	$	—	$	282.5	$	—
U.S. small/mid cap equity portfolios (2)		47.3		—		—		47.3		—
Balanced asset portfolios (3)		101.4		—		—		101.4		—
International equity portfolios (4)		143.9		—		—		143.9		—
Real estate investment portfolios (6)		238.4		—		—		238.4		—
Single client separate account investments:
Fixed income securities:
U.S. government and agencies		447.0		—		447.0		—		—
States and political subdivisions		25.0		—		—		25.0		—
Corporate		1,336.9		—		—		1,336.9		—
Commercial mortgage-backed securities		16.1		—		—		16.1		—
Other debt obligations		4.1		—		—		4.1		—
Hedge funds (7)		27.9		27.9		—		—		—
Pooled separate account investment (8)		43.7		—		—		43.7		—
Other (9)		12.1		—		—		12.1		—
Total	$	2,726.3	$	27.9	$	447.0	$	2,251.4	$	—

(1) The portfolios invest primarily in publicly traded equity securities of large U.S. companies.

(2) The portfolios invest primarily in publicly traded equity securities of mid-sized and small U.S. companies.

(3) The portfolios are a combination of underlying fixed income and equity investment options. These investment options may include balanced, asset allocation, target-date and target-risk investment options. Although typically lower risk than investment options that invest solely in equities, all investment options in this category have the potential to lose value.

(4) The portfolios invest primarily in publicly traded equity securities of non-U.S. companies.

(5) The portfolios invest primarily in fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, residential mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations.

(6) The portfolios invest primarily in U.S. commercial real estate properties through a separate account.

(7) The hedge funds have varying investment strategies that also have a variety of redemption terms and conditions. We do not have unfunded commitments associated with these hedge funds.

(8) The single client separate accounts invest in a money market pooled separate account.

(9) Includes cash and net (payables)/receivables for the single client separate accounts.

Target Asset Allocation (Table)

Asset category	Target allocation
Fixed income security portfolios	25	%	-	80	%
Equity portfolios	5	%	-	60	%
Private investments	10	%	-	20	%

Other postretirement benefits

Defined Benefit Plans and Other Postretirement Benefit Plans

Fair Value of Plan Assets (Table)

	December 31, 2023
	Assets		Fair value hierarchy level
	measured at
	fair value		Level 1		Level 2		Level 3
	(in millions)
Asset category
Cash and cash equivalents	$	1.3	$	1.3	$	—	$	—
Fixed income security portfolios (1)		47.9		47.9		—		—
U.S. equity portfolios (2)		36.7		36.7		—		—
International equity portfolios (3)		13.9		13.9		—		—
Total	$	99.8	$	99.8	$	—	$	—

	December 31, 2022
	Assets		Fair value hierarchy level
	measured at
	fair value		Level 1		Level 2		Level 3
	(in millions)
Asset category
Cash and cash equivalents	$	0.6	$	0.6	$	—	$	—
Fixed income security portfolios (1)		47.6		47.6		—		—
U.S. equity portfolios (2)		33.6		33.6		—		—
International equity portfolios (3)		12.6		12.6		—		—
Total	$	94.4	$	94.4	$	—	$	—

(1) The portfolios invest in various fixed income securities, primarily of U.S. origin. These include, but are not limited to, corporate bonds, residential mortgage-backed securities, commercial mortgage-backed securities, U.S. Treasury securities, agency securities, asset-backed securities and collateralized mortgage obligations.

(2) The portfolios invest primarily in publicly traded equity securities of large U.S. companies.

(3) The portfolios invest primarily in publicly traded equity securities of non-U.S. companies.

Target Asset Allocation (Table)

Asset category	Target allocation
Fixed income security portfolios	50	%
U.S. equity portfolios	35	%
International equity portfolios	15	%