Market Risk Benefits - Net Asset (Liability) Balances and Changes in Valuation of MRBs for Asia - Guaranteed Pension (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
The net asset (liability) balances and the changes in the valuation of the MRBs
Balance at beginning of period	$ (98.2)
Balance at end of period	(87.1)	$ (98.2)
Market Risk Benefit, Net Amount at Risk				$ 644.6
Principal Asset Management | Principal International | Guaranteed pension | Asia
The net asset (liability) balances and the changes in the valuation of the MRBs
Balance at beginning of period	(26.0)	(35.1)	$ (53.3)
Effect of changes in nonperformance risk at beginning of period	1.2	4.3	(6.5)
Adjusted balance at beginning of period	(24.8)	(30.8)	(46.8)
Interest accrual and expected policyholder behavior	(2.8)	(7.1)	(5.3)
Benefit payments	3.7	9.5	5.7
Changes in interest rates	0.7	3.9	7.6
Changes in equity markets	0.1	(1.0)	1.4
Actual policyholder behavior different from expected behavior	0.4	0.7	3.6
Foreign currency translation adjustment	0.1
Adjusted balance at end of period	(22.6)	(24.8)	(30.8)
Effect of changes in nonperformance risk at end of period	1.4	1.2	4.3
Balance at end of period	$ (24.0)	$ (26.0)	$ (35.1)
Market Risk Benefit, Weighted Average Attained Age	50 years	50 years
Market Risk Benefit, Net Amount at Risk	$ 87.4	$ 91.0