Goodwill and Other Intangible Assets - Changes in Goodwill (Details) - USD ($) $ in Millions |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2026 |
Dec. 31, 2025 |
|
| Changes in Goodwill | ||
| Beginning balance, Goodwill | $ 1,600.5 | $ 1,549.7 |
| Goodwill from acquisitions | 325.4 | |
| Goodwill disposed | (41.0) | |
| Foreign currency, Goodwill | (24.3) | 50.8 |
| Ending balance, Goodwill | 1,860.6 | 1,600.5 |
| Retirement and Income Solutions | ||
| Changes in Goodwill | ||
| Beginning balance, Goodwill | 687.2 | 687.2 |
| Ending balance, Goodwill | 687.2 | 687.2 |
| Principal Asset Management | ||
| Changes in Goodwill | ||
| Beginning balance, Goodwill | 883.8 | 833.0 |
| Goodwill disposed | (41.0) | |
| Foreign currency, Goodwill | (24.3) | 50.8 |
| Ending balance, Goodwill | 818.5 | 883.8 |
| Benefits and Protection | ||
| Changes in Goodwill | ||
| Beginning balance, Goodwill | 29.5 | 29.5 |
| Goodwill from acquisitions | 325.4 | |
| Ending balance, Goodwill | $ 354.9 | $ 29.5 |
| X | ||||||||||
- Definition Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Definition Amount of foreign currency translation gain (loss) which increases (decreases) asset representing future economic benefit from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. No definition available.
|
| X | ||||||||||
- Definition Amount of decrease in goodwill acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized, from divestiture. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|