XML 66 R50.htm IDEA: XBRL DOCUMENT
v3.24.0.1

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 | %

X
- Definition Tabular disclosure of the assumptions used to determine for pension plans and/or other employee benefit plans the benefit obligation, including assumed discount rate and rate of compensation increase. + References No definition available. + Details
Name: | pfg_ScheduleOfBenefitObligationAssumptionsUsedTableTextBlock
Namespace Prefix: | pfg_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of supplemental information for defined benefit pension plans, separately showing information for qualified and non-qualified plans. + References No definition available. + Details
Name: | pfg_ScheduleOfDefinedBenefitPensionPlansSupplementalInformationTableTextBlock
Namespace Prefix: | pfg_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the assumptions used to determine for pension plans and/or other employee benefit plans the net periodic benefit cost, including assumed discount rate, expected long-term rate of return on plan assets, and rate of compensation increase. + References No definition available. + Details
Name: | pfg_ScheduleOfNetPeriodicBenefitCostAssumptionsUsedTableTextBlock
Namespace Prefix: | pfg_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the overall target allocation of plan assets of pension plans and/or other employee benefit plans by asset category. + References No definition available. + Details
Name: | pfg_ScheduleOfTargetAllocationOfPlanAssetsTableTextBlock
Namespace Prefix: | pfg_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of benefit obligation and plan assets of defined benefit plan with accumulated benefit obligation in excess of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-3 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-3 + Details
Name: | us-gaap_ScheduleOfAccumulatedBenefitObligationsInExcessOfFairValueOfPlanAssetsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the major categories of plan assets of pension plans and/or other employee benefit plans. This information may include, but is not limited to, the target allocation of plan assets, the fair value of each major category of plan assets, and the level within the fair value hierarchy in which the fair value measurements fall. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 715 -SubTopic 20 -Subparagraph (d)(5) -Name Accounting Standards Codification -Paragraph 1 -Section 50 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_ScheduleOfAllocationOfPlanAssetsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the net gain (loss) and net prior service cost or credit recognized in other comprehensive income (loss) for the period for pension plans and/or other employee benefit plans, and reclassification adjustments of other comprehensive income (loss) for the period, as those amounts, including amortization of the net transition asset or obligation, are recognized as components of net periodic benefit cost. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_ScheduleOfAmountsRecognizedInOtherComprehensiveIncomeLossTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of benefits expected to be paid by pension plans and/or other employee benefit plans in each of the next five fiscal years and in the aggregate for the five fiscal years thereafter. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 715 -SubTopic 20 -Subparagraph (f) -Name Accounting Standards Codification -Paragraph 1 -Section 50 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the assumed health care cost trend rates for the next year used to measure the expected cost of benefits covered by the plans, including the ultimate trend rate(s) and when that rate is expected to be achieved. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 715 -SubTopic 20 -Subparagraph (l) -Name Accounting Standards Codification -Paragraph 1 -Section 50 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_ScheduleOfHealthCareCostTrendRatesTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 715 -SubTopic 20 -Subparagraph (h) -Name Accounting Standards Codification -Paragraph 1 -Section 50 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_ScheduleOfNetBenefitCostsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of net funded status of pension plans and/or other employee benefit plans. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_ScheduleOfNetFundedStatusTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |