Separate Account Balances - Separate Account Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022	Dec. 31, 2021
Separate Account Balances
Separate account liabilities	$ 155,478.2	$ 155,375.1
Other balances
Separate Account Balances
Separate account liabilities	237.3	233.3
Retirement and Income Solutions
Separate Account Balances
Separate account liabilities	117,251.7	115,899.1
Retirement and Income Solutions | Group retirement contracts
Separate Account Balances
Separate account liabilities	108,677.4	107,240.1	$ 131,188.6
Retirement and Income Solutions | Individual variable annuities
Separate Account Balances
Separate account liabilities	8,574.3	8,659.0	11,000.0
Principal Asset Management | Principal International
Separate Account Balances
Separate account liabilities	32,572.9	34,231.7
Principal Asset Management | Principal International | Pension | Latin America
Separate Account Balances
Separate account liabilities	31,680.8	33,316.7	33,030.6
Principal Asset Management | Principal International | Guaranteed pension | Asia
Separate Account Balances
Separate account liabilities	892.1	915.0	971.3
Benefits and Protection | Life Insurance | Universal life
Separate Account Balances
Separate account liabilities	$ 5,416.3	$ 5,011.0	$ 5,886.1