Nature of Operations and Significant Accounting Policies - Liability for Future Policy Benefits (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Recent Accounting Pronouncements
Liability for future policy benefits	$ 35,620.8	$ 34,064.4		$ 43,489.8
Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits	27,238.4	26,230.8		33,009.5
Benefits and Protection
Recent Accounting Pronouncements
Liability for future policy benefits	2,777.1	2,607.8		3,661.2
Pension risk transfer | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits	22,146.1	21,211.4		25,863.7
Individual fixed income annuities | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits	5,092.3	5,019.4		7,145.8
Individual fixed income annuities | Principal Asset Management | Principal International | Latin America
Recent Accounting Pronouncements
Liability for future policy benefits	5,416.9	5,042.3		6,561.5
Individual disability | Benefits and Protection | Specialty Benefits
Recent Accounting Pronouncements
Liability for future policy benefits	1,815.9	1,698.8	$ 2,498.4	2,500.9
Term life | Benefits and Protection | Life Insurance
Recent Accounting Pronouncements
Liability for future policy benefits	961.2	909.0	1,117.6	1,160.3
Long-term care insurance | Corporate
Recent Accounting Pronouncements
Liability for future policy benefits	$ 188.4	$ 183.5	$ 234.7	257.6
Previously Reported [Member]
Recent Accounting Pronouncements
Liability for future policy benefits				36,310.8
Previously Reported [Member] | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				28,130.0
Previously Reported [Member] | Benefits and Protection
Recent Accounting Pronouncements
Liability for future policy benefits				3,008.3
Previously Reported [Member] | Pension risk transfer | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				21,982.8
Previously Reported [Member] | Individual fixed income annuities | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				6,147.2
Previously Reported [Member] | Individual fixed income annuities | Principal Asset Management | Principal International | Latin America
Recent Accounting Pronouncements
Liability for future policy benefits				5,038.4
Previously Reported [Member] | Individual disability | Benefits and Protection | Specialty Benefits
Recent Accounting Pronouncements
Liability for future policy benefits				2,173.8
Previously Reported [Member] | Term life | Benefits and Protection | Life Insurance
Recent Accounting Pronouncements
Liability for future policy benefits				834.5
Previously Reported [Member] | Long-term care insurance | Corporate
Recent Accounting Pronouncements
Liability for future policy benefits				134.1
Adjustment for reversal of unrealized gain (loss) from AOCI
Recent Accounting Pronouncements
Liability for future policy benefits				(1,965.3)
Adjustment for reversal of unrealized gain (loss) from AOCI | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				(1,162.0)
Adjustment for reversal of unrealized gain (loss) from AOCI | Benefits and Protection
Recent Accounting Pronouncements
Liability for future policy benefits				(168.7)
Adjustment for reversal of unrealized gain (loss) from AOCI | Pension risk transfer | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				(947.0)
Adjustment for reversal of unrealized gain (loss) from AOCI | Individual fixed income annuities | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				(215.0)
Adjustment for reversal of unrealized gain (loss) from AOCI | Individual fixed income annuities | Principal Asset Management | Principal International | Latin America
Recent Accounting Pronouncements
Liability for future policy benefits				(634.6)
Adjustment for reversal of unrealized gain (loss) from AOCI | Individual disability | Benefits and Protection | Specialty Benefits
Recent Accounting Pronouncements
Liability for future policy benefits				(168.7)
Adjustment under the modified retrospective approach
Recent Accounting Pronouncements
Liability for future policy benefits				101.2
Adjustment under the modified retrospective approach | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				0.1
Adjustment under the modified retrospective approach | Benefits and Protection
Recent Accounting Pronouncements
Liability for future policy benefits				9.4
Adjustment under the modified retrospective approach | Individual fixed income annuities | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				0.1
Adjustment under the modified retrospective approach | Individual fixed income annuities | Principal Asset Management | Principal International | Latin America
Recent Accounting Pronouncements
Liability for future policy benefits				61.7
Adjustment under the modified retrospective approach | Individual disability | Benefits and Protection | Specialty Benefits
Recent Accounting Pronouncements
Liability for future policy benefits				2.4
Adjustment under the modified retrospective approach | Term life | Benefits and Protection | Life Insurance
Recent Accounting Pronouncements
Liability for future policy benefits				7.0
Adjustment under the modified retrospective approach | Long-term care insurance | Corporate
Recent Accounting Pronouncements
Liability for future policy benefits				30.0
Effect of remeasurement at the current discount rate
Recent Accounting Pronouncements
Liability for future policy benefits				9,043.1
Effect of remeasurement at the current discount rate | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				6,041.4
Effect of remeasurement at the current discount rate | Benefits and Protection
Recent Accounting Pronouncements
Liability for future policy benefits				812.2
Effect of remeasurement at the current discount rate | Pension risk transfer | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				4,827.9
Effect of remeasurement at the current discount rate | Individual fixed income annuities | Retirement and Income Solutions
Recent Accounting Pronouncements
Liability for future policy benefits				1,213.5
Effect of remeasurement at the current discount rate | Individual fixed income annuities | Principal Asset Management | Principal International | Latin America
Recent Accounting Pronouncements
Liability for future policy benefits				2,096.0
Effect of remeasurement at the current discount rate | Individual disability | Benefits and Protection | Specialty Benefits
Recent Accounting Pronouncements
Liability for future policy benefits				493.4
Effect of remeasurement at the current discount rate | Term life | Benefits and Protection | Life Insurance
Recent Accounting Pronouncements
Liability for future policy benefits				318.8
Effect of remeasurement at the current discount rate | Long-term care insurance | Corporate
Recent Accounting Pronouncements
Liability for future policy benefits				$ 93.5