Schedule III - Supplementary Insurance Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Supplementary Insurance Information
Deferred acquisition costs	$ 4,686.9	$ 3,757.5	$ 3,409.7	$ 3,521.3
Future policy benefits and claims	44,874.9	43,948.1
Contractholder and other policyholder funds	43,787.8	44,669.0
Premiums and other considerations	5,339.7	4,841.5	6,037.4
Net investment income	3,830.4	4,406.1	3,890.6
Benefits, claims and settlement expenses	6,370.8	7,097.0	8,281.5
Amortization of deferred acquisition costs	384.4	285.4	388.1
Other operating expenses	4,581.5	4,701.9	4,258.4
Retirement and Income Solutions
Supplementary Insurance Information
Deferred acquisition costs	1,271.5	819.4
Future policy benefits and claims	28,322.9	27,716.5
Contractholder and other policyholder funds	35,262.8	35,941.4
Premiums and other considerations	1,959.7	1,883.6	3,221.0
Net investment income	2,252.2	2,674.4	2,457.9
Benefits, claims and settlement expenses	3,228.6	3,450.1	4,899.4
Amortization of deferred acquisition costs	134.2	116.7	82.2
Other operating expenses	1,606.8	1,715.2	1,578.2
Principal Global Investors
Supplementary Insurance Information
Net investment income	13.1	3.9	5.6
Other operating expenses	1,093.5	1,128.6	1,029.6
Principal International
Supplementary Insurance Information
Deferred acquisition costs	7.5	8.4
Future policy benefits and claims	4,275.1	3,813.5
Contractholder and other policyholder funds	942.3	1,047.2
Premiums and other considerations	77.7	127.5	156.6
Net investment income	818.7	631.1	446.8
Benefits, claims and settlement expenses	697.5	610.0	440.7
Amortization of deferred acquisition costs	1.0	1.2	1.2
Other operating expenses	432.6	469.1	416.8
U.S. Insurance Solutions
Supplementary Insurance Information
Deferred acquisition costs	3,407.9	2,929.7
Future policy benefits and claims	12,128.2	12,262.1
Contractholder and other policyholder funds	7,943.3	8,039.6
Premiums and other considerations	3,306.5	2,830.4	2,659.8
Net investment income	564.2	917.1	850.6
Benefits, claims and settlement expenses	2,421.1	3,031.7	2,937.2
Amortization of deferred acquisition costs	249.2	167.5	304.7
Other operating expenses	1,027.9	998.2	936.9
Corporate
Supplementary Insurance Information
Future policy benefits and claims	148.7	156.0
Contractholder and other policyholder funds	(360.6)	(359.2)
Premiums and other considerations	(4.2)
Net investment income	182.2	179.6	129.7
Benefits, claims and settlement expenses	23.6	5.2	4.2
Other operating expenses	$ 420.7	$ 390.8	$ 296.9