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Employee and Agent Benefits | 12 Months Ended
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Dec. 31, 2023
Employee and Agent Benefits |
Employee and Agent Benefits | 15. Employee and Agent Benefits We provide a U.S. qualified defined benefit pension plan, covering U.S. employees that meet certain eligibility requirements and certain agents contracted on or before December 31, 2018. A final average pay benefit formula has been in place for plan participants employed prior to January 1, 2002. For agents, this formula ended on December 31, 2018, and for employees the formula ended on December 31, 2022. The final average pay benefit is based on the years of service and generally the employee’s or agent’s average annual compensation during the last five years prior to the earliest of termination, retirement or the formula end date. A cash balance benefit was added on January 1, 2002. A participant’s cash balance account is credited with an amount based on the participant’s salary, age and service. These credits accrue with interest. For plan participants hired on and after January 1, 2002, only the cash balance benefit applies. For pre-2002 participants, the pension benefit earned prior to the final average pay formula end date is the greater of the final average pay benefit or the cash balance benefit earned before the end date. They will also earn a new cash balance benefit for service after the formula end date. In addition, we sponsor non-qualified defined benefit plans subject to Section 409A of the Internal Revenue Code. This plan is for certain highly compensated employees and agents to replace the benefit that cannot be provided by the qualified defined benefit pension plan due to IRS limits. These nonqualified plans generally parallel the qualified plan but offer different payment options. No agent will become a new participant in the nonqualified plan after December 31, 2018. We provide certain health care, life insurance and long-term care benefits for retired employees, their beneficiaries and covered dependents (“other postretirement benefits”). While virtually all U.S. employees continue to have access to the postretirement health care and life insurance benefits, only those U.S. employees that were hired prior to January 1, 2002, and retired prior to January 1, 2011, (post-65 medical) or January 1, 2020, (life insurance and pre-65 medical) were eligible to receive subsidized benefits. All others pay the full cost of coverage. The long-term care plan was subsidized only for those who retired prior to January 1, 2000, and is no longer accessible. The subsidy level for all benefits varies by plan, age, service and retirement date. The funding policy for all employee benefit plans is to fund the cost of providing pension benefits in the years that the employees and agents are providing service, taking into account the funding status of the trust. For the qualified defined benefit plan, this policy will be subject to an amount no lower than the minimum annual contribution required under the Employee Retirement Income Security Act (“ERISA”), and, generally, not greater than the maximum amount that can be deducted for U.S. federal income tax purposes. While we designate assets to cover the computed liability of the nonqualified pension plan, the assets are not included as part of the asset balances presented in this footnote as they do not qualify as plan assets in accordance with U.S. GAAP. Obligations and Funded Status The plans’ combined funded status, reconciled to amounts recognized in the consolidated statements of financial position, was as follows: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | 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) | ​
​ The accumulated benefit obligation for all defined benefit pension plans was $3,390.9 million and $3,209.4 million as of December 31, 2023 and 2022, respectively. ​ Employer contributions to the pension plans include contributions made directly to the qualified pension plan assets and contributions from corporate assets to pay nonqualified pension benefits. Benefits paid from the pension plans include both qualified and nonqualified plan benefits. Nonqualified pension plan assets are not included as part of the asset balances presented in this footnote. The nonqualified pension plan assets are held in Rabbi trusts for the benefit of all nonqualified plan participants. The assets held in a Rabbi trust are available to satisfy the claims of general creditors only in the event of bankruptcy. Therefore, these assets are fully consolidated in our consolidated statements of financial position and are not reflected in our funded status as they do not qualify as plan assets under U.S. GAAP. The market value of assets held in these trusts was $342.2 million and $336.7 million as of December 31, 2023 and 2022, respectively. Pension Plan Changes and Plan Gains/Losses For the year ended December 31, 2023, the pension plans had an actuarial loss primarily due to a decrease in discount rate. For the year ended December 31, 2022, the pension plans had an actuarial gain primarily due to an increase in discount rate. Other Postretirement Plan Changes and Plan Gains/Losses For the year ended December 31, 2023, the other postretirement benefit plans had an actuarial loss primarily due to a decrease in the discount rates and actual medical claims costs being higher than previously expected. For the year ended December 31, 2022, the other postretirement benefit plans had an actuarial gain primarily due to an increase in the discount rates and actual medical claims costs being lower than previously expected. Information for Pension Plans With an Accumulated Benefit Obligation in Excess of Plan Assets For 2023 and 2022, both the qualified and nonqualified plans had accumulated benefit obligations in excess of plan assets. As noted previously, the nonqualified plans have assets that are deposited in trusts that fail to meet the U.S. GAAP requirements to be included in plan assets; however, these assets are included in our consolidated statements of financial position. ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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 | ​
​ We did not have any other postretirement benefit plans with an accumulated postretirement benefit obligation in excess of plan assets. ​ Components of Net Periodic Benefit Cost ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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) | ​
​ The components of net periodic benefit cost including the service cost component are included in operating expenses on the consolidated statements of operations. The pension plans’ actuarial gains and losses are amortized using a straight-line amortization method over the average remaining service period of plan participants. The other postretirement plans use a straight-line amortization over the average future lifetime of its remaining covered group of retirees. For the qualified pension plan, gains and losses are amortized without use of the 10% allowable corridor. For the nonqualified pension plans and other postretirement benefit plans, the corridors allowed are used. ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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
​ Net actuarial (gain) loss and net prior service cost benefit have been recognized in AOCI. ​ Assumptions Weighted-average assumptions used to determine benefit obligations as disclosed under the Obligations and Funded Status section ​
​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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 ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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 | ​
​ The assumed salary growth rates used to project benefits for the projected benefit obligation are age-based for home office employees. The rate labeled cash balance benefit (relative to employees accruing a cash balance) is the lifecount-weighted average rate of salary growth in the coming year only, as the impact of salary assumption for cash balance benefits are limited to the upcoming year service cost. The rate labeled traditional benefit (relative to employees still accruing a final average pay benefit) is the lifecount-weighted average (at each age) of the single annual growth rate at the age that is equivalent to applying the scale from that age to assumed termination or retirement ages. For the December 31, 2021, pension benefit obligation and going forward, one average rate of compensation increase is disclosed for all participants as the traditional benefit is frozen as of December 31, 2022. For the pension benefits, the discount rate is determined by projecting future benefit payments inherent in the projected benefit obligation and discounting those cash flows using a spot yield curve for high quality corporate bonds. The plans’ expected benefit payments are discounted to determine a present value using the yield curve and the discount rate is the level rate that produces the same present value. The expected return on plan assets is the long-term rate we expect to be earned based on the long-term investment policy of the plans and the various classes of invested funds. A weighted average rate was developed based on those overall rates and the target asset allocation of the plans. For other postretirement benefits, the discount rate is determined by projecting future benefit payments inherent in the accumulated postretirement benefit obligation and discounting those cash flows using a spot yield curve for high quality corporate bonds. The plans’ expected benefit payments are discounted to determine a present value using the yield curve and the discount rate is the level rate that produces the same present value. The 5.05% expected long-term return on plan assets for 2023 was based on the weighted average expected long-term asset returns for the plans. The expected long-term rates for the home office and agent pre-65 medical/life plans and post-65 medical plans were 5.2% and 4.6%, respectively. Assumed Health Care Cost Trend Rates Used to Determine Net Periodic Benefit Cost ​
​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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 | ​
​ Pension Plan and Other Postretirement Benefit Plan Assets Fair value is defined as the price that would be received to sell an asset in an orderly transaction between market participants at the measurement date (an exit price). The fair value hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels.
| ● | Level 1 – Fair values are based on unadjusted quoted prices in active markets for identical assets.
| ● | Level 2 – Fair values are based on inputs other than quoted prices within Level 1 that are observable for the asset, either directly or indirectly.
| ● | Level 3 – Fair values are based on significant unobservable inputs for the asset.
Our pension plan assets consist of investments in pooled separate accounts and single client separate accounts. Net asset value (“NAV”) of the pooled separate accounts is calculated in a manner consistent with U.S. GAAP for investment companies and is determinative of their fair value. Several of the pooled separate accounts invest in publicly quoted mutual funds or actively managed stocks. The fair value of the underlying mutual funds or stocks is used to determine the NAV of the separate account, which is not publicly quoted. Some of the pooled separate accounts also invest in fixed income securities. The fair value of the underlying securities is based on quoted prices of similar assets and used to determine the NAV of the separate account. Some of the pooled separate accounts invest in real estate properties. The fair value is based on discounted cash flow valuation models that utilize public real estate market data inputs such as transaction prices, market rent growth, vacancy levels, leasing absorption, market capitalization rates and discount rates. The single client separate accounts invest in fixed income securities, hedge funds, a pooled separate account investment and other assets. The fixed income securities include U.S. Treasury bonds for which the fair value is based on quoted prices of identical assets in active markets. The fair value of the other fixed income securities is determined either from prices obtained from third party pricing vendors who use observable market information to determine prices or from internal models using substantially all observable inputs or a matrix pricing valuation approach. The hedge funds are measured at fair value using the NAV per share (or its equivalent) practical expedient and have not been classified in the fair value hierarchy. The NAV of the pooled separate account investment is calculated in a manner consistent with U.S. GAAP for investment companies and is determinative of its fair value. The carrying amounts of other assets, which are highly liquid in nature, are used to approximate fair value. Our other postretirement benefit plan assets consist of cash, investments in fixed income security portfolios and investments in equity security portfolios. Because of the nature of cash, its carrying amount approximates fair value. The fair value of fixed income investment funds, U.S. equity portfolios and international equity portfolios is based on quoted prices in active markets for identical assets. Pension Plan Assets The fair value of the qualified pension plan’s assets by asset category as of the most recent measurement date was as follows: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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.
We have established an investment policy that provides the investment objectives and guidelines for the pension plan. Our investment strategy is to achieve the following:
| ● | Obtain a reasonable long-term return consistent with the level of risk assumed and at a cost of operation within prudent levels. Performance benchmarks are monitored.
| ● | Ensure sufficient liquidity to meet the emerging benefit liabilities for the plan.
| ● | Provide for diversification of assets in an effort to avoid the risk of large losses and maximize the investment return to the pension plan consistent with market and economic risk.
In administering the qualified pension plan’s asset allocation strategy, we consider the projected liability stream of benefit payments, the relationship between current and projected assets of the plan and the projected actuarial liabilities streams, the historical performance of capital markets adjusted for the perception of future short- and long-term capital market performance and the perception of future economic conditions. According to our investment policy, the target asset allocation for the qualified plan is: ​
​ | ​ | ​ | ​ | ​ | ​ | ​
Asset category |  | Target allocation | ​
Fixed income security portfolios | ​ | 25 | % | - | 80 | %
Equity portfolios | ​ | 5 | % | - | 60 | %
Private investments | ​ | 10 | % | - | 20 | %
​ Other Postretirement Benefit Plan Assets The fair value of the other postretirement benefit plans’ assets by asset category as of the most recent measurement date was as follows: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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.
The investment strategies for the other postretirement benefit plans are similar to those employed by the qualified pension plan. According to our investment policy, the target asset allocation for the other postretirement benefit plans is: ​
​ | ​ | ​ | ​
Asset category |  | Target allocation | ​
Fixed income security portfolios | ​ | 50 | %
U.S. equity portfolios | ​ | 35 | %
International equity portfolios | ​ | 15 | %
​ Contributions Our funding policy for our qualified pension plan is to fund the plan annually in an amount at least equal to the minimum annual contribution required under ERISA and, generally, not greater than the maximum amount that can be deducted for U.S. federal income tax purposes. We do not anticipate contributions will be needed to satisfy the minimum funding requirements of ERISA for our qualified plan. We are unable to estimate the amount that may be contributed, but it is possible that we may fund the plans in 2024 up to $75.0 million. This includes funding for both our qualified and nonqualified pension plans. While we designate assets to cover the computed liability of the nonqualified plan, the assets are not included as part of the asset balances presented in this footnote as they do not qualify as plan assets in accordance with U.S. GAAP. We may contribute to our other postretirement benefit plans in 2024 pending future analysis. Estimated Future Benefit Payments The estimated future benefit payments, which reflect expected future service, are: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ |  | ​ | ​ | 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 | ​
​ The above table reflects the total estimated future benefits to be paid from the plan, including both our share of the benefit cost and the participants’ share of the cost, which is funded by their contributions to the plan. The assumptions used in calculating the estimated future benefit payments are the same as those used to measure the benefit obligation for the year ended December 31, 2023. ​ Defined Benefit Pension Plans Supplemental Information Certain key summary data is shown below separately for qualified and nonqualified plans. ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | 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) | ​
​ Defined Contribution and Deferred Compensation Plans In addition, we have defined contribution plans that are generally available to all U.S. employees and agents. Eligible participants could not contribute more than $22,500 of their compensation to the plans in 2023. Effective January 1, 2006, we made several changes to the retirement programs. In general, the pension and supplemental executive retirement plan benefit formulas were reduced and the 401(k) matching contribution was increased. Employees who were ages 47 or older with at least ten years of service on December 31, 2005, could elect to retain the prior benefit provisions and forgo receipt of the additional matching contributions. The employees who elected to retain the prior benefit provisions are referred to as “Grandfathered Choice Participants.” We match the Grandfathered Choice Participant’s contribution at a 50% contribution rate up to a maximum matching contribution of 3% of the participant’s compensation. For all other participants, we match the participant’s contributions at a 75% contribution rate up to a maximum matching contribution of 6% of the participant’s compensation. The defined contribution plans allow employees to choose among various investment options, including our common stock, which is available through our Employee Stock Ownership Plan (“ESOP”). We contributed $74.1 million, $70.3 million and $60.5 million in 2023, 2022 and 2021, respectively, to our qualified defined contribution plans. ​ The number of shares of our common stock allocated to participants in the ESOP was 1.7 million and 1.8 million as of December 31, 2023 and 2022, respectively. As of December 31, 2023 and 2022, the fair value of the ESOP, which includes earned and unearned common stock, was $135.6 million and $148.4 million, respectively. The ESOP’s total assets include our common stock and cash. The ESOP purchases our common stock on the open market. The number of shares of our common stock held within the ESOP is treated as outstanding in both our basic and diluted earnings per share calculations. We also have nonqualified deferred compensation plans available to select employees and agents that allow them to defer compensation amounts in excess of limits imposed by U.S. federal tax law with respect to the qualified plans. For certain nonqualified deferred compensation plans that include an employer matching contribution, in 2023 we matched the Grandfathered Choice Participant’s deferral at a 50% match deferral rate up to a maximum matching deferral of 3% of the participant’s compensation. For all other participants in nonqualified deferred compensation plans that include an employer matching contribution, we matched the participant’s deferral at a 75% match deferral rate up to a maximum matching deferral of 6% of the participant’s compensation. We contributed $3.1 million, $3.9 million and $3.4 million in 2023, 2022 and 2021, respectively, to our nonqualified deferred compensation plans.

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