Segment Information - Reconciliation of Segment Assets to Consolidated (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Segment Information: Assets
Total assets	$ 287,948.0	$ 290,578.3
Retirement and Income Solutions
Segment Information: Assets
Total assets	201,802.1	202,294.2
Principal Asset Management
Segment Information: Assets
Total assets	43,789.9	45,950.7
Benefits and Protection
Segment Information: Assets
Total assets	41,707.7	40,048.3
Corporate
Segment Information: Assets
Total assets	$ 648.3	$ 2,285.1