Future Policy Benefits and Claims - Principal Asset Management - Principal International (Details) - Principal Asset Management - Principal International - Latin America - Individual fixed income annuities - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Present value of expected future policy benefit payments
Balance at beginning of period, Present value of expected future policy benefit payments	$ 5,042.3	$ 4,336.8	$ 6,561.5
Effect of changes in discount rate assumptions at beginning of period	(754.6)	(478.5)	(2,096.0)
Balance at beginning of period at original discount rate	4,287.7	3,858.3	4,465.5
Effect of actual variances from expected experience	0.9	(4.7)	(4.9)
Adjusted beginning of period balance at original discount rate	4,288.6	3,853.6	4,460.6
Interest accrual	385.8	662.0	444.3
Benefit payments	(355.9)	(325.8)	(436.0)
Issuances	30.0	86.4	141.3
Foreign currency translation adjustment	(106.6)	11.5	(751.9)
Balance at end of period at original discount rate	4,241.9	4,287.7	3,858.3
Effect of changes in discount rate assumptions at end of period	351.8	754.6	478.5
Balance at end of period, Present value of expected future policy benefit payments	$ 4,593.7	$ 5,042.3	$ 4,336.8
Weighted-average duration for future policy benefits (in years)	9 years 10 months 24 days	10 years 10 months 24 days
Increase (decrease) to LFPB due to effect of changes in discount rate assumptions	$ (402.8)	$ 276.1