Separate Account Balances - Principal Asset Management - Principal International (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Changes in separate account liabilities
Balance at beginning of period	$ 155,375.1
Balance at end of period	155,478.2	$ 155,375.1
Principal Asset Management | Principal International
Changes in separate account liabilities
Balance at beginning of period	34,231.7
Balance at end of period	32,572.9	34,231.7
Principal Asset Management | Principal International | Pension | Latin America
Changes in separate account liabilities
Balance at beginning of period	33,316.7	33,030.6
Premiums and deposits	2,786.4	3,620.4
Policy charges	(13.7)	(18.2)
Surrenders, withdrawals and benefit payments	(3,215.3)	(3,984.6)
Investment performance	396.7	498.8
Other	2.7	(0.8)
Foreign currency translation adjustment	(1,592.7)	170.5
Balance at end of period	31,680.8	33,316.7
Cash surrender value	31,680.8	33,316.7
Principal Asset Management | Principal International | Guaranteed pension | Asia
Changes in separate account liabilities
Balance at beginning of period	915.0	971.3
Premiums and deposits	166.8	276.2
Policy charges	(14.7)	(19.8)
Surrenders, withdrawals and benefit payments	(201.0)	(247.0)
Investment performance	29.3	(64.0)
Other	(0.2)	(0.4)
Foreign currency translation adjustment	(3.1)	(1.3)
Balance at end of period	892.1	915.0
Cash surrender value	$ 892.1	$ 915.0