Stockholders' Equity - AOCI and Noncontrolling Interest (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Change in accumulated other comprehensive income (loss) rollforward
Balances		$ 16,069.4
Adjustment for reinsurance		1,572.3
Purchase of subsidiary shares from noncontrolling interest	[1]	(8.1)	$ (18.1)	$ (1.4)
Adjustment for reinsurance		131.8
Balances		10,001.7	16,069.4
Change in redeemable noncontrolling interest rollforward
Redeemable noncontrolling interest, balance at beginning of period		332.5	255.6	264.9
Net income (loss) attributable to redeemable noncontrolling interest		(25.8)	17.5	7.5
Redeemable noncontrolling interest of deconsolidated entities		(2.8)	(37.4)	(91.9)
Contributions from redeemable noncontrolling interest		67.3	166.8	136.2
Distributions to redeemable noncontrolling interest		(108.9)	(66.8)	(62.0)
Purchase of subsidiary shares from redeemable noncontrolling interest		(1.1)	(6.1)
Change in redemption value of redeemable noncontrolling interest		(0.2)	3.1	0.2
Other comprehensive income (loss) attributable to redeemable noncontrolling interest		0.9	(0.2)	0.6
Redeemable noncontrolling interest, balance at end of period		262.0	332.5	255.6
Stock-based compensation attributable to redeemable noncontrolling interest		0.1		0.1
Accumulated other comprehensive income (loss)
Change in accumulated other comprehensive income (loss) rollforward
Balances		1,610.9	2,383.1	1,037.9
Other comprehensive income (loss) during the period, net of adjustments		(9,257.9)	(823.5)	1,329.2
Amounts reclassified to accumulated other comprehensive income (loss)		316.2	51.3	16.0
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		(8,941.7)	(772.2)	1,345.2
Adjustment for reinsurance		131.8
Balances		(7,199.0)	1,610.9	2,383.1
Net unrealized gains (losses) on available-for-sale securities
Change in accumulated other comprehensive income (loss) rollforward
Balances		3,467.4	4,138.3	2,806.0
Other comprehensive income (loss) during the period, net of adjustments		(9,300.0)	(685.2)	1,416.7
Amounts reclassified to accumulated other comprehensive income (loss)		311.3	14.3	(40.3)
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		(8,988.7)	(670.9)	1,376.4
Adjustment for reinsurance		124.4
Balances		(5,396.9)	3,467.4	4,138.3
Net unrealized gains (losses) on available-for-sale debt securities with allowance for credit losses		0.3	(2.1)	2.9
Net unrealized gains (losses) on available-for-sale securities | ASU 2016-13 - CECL | Effects of implementation of accounting change
Change in accumulated other comprehensive income (loss) rollforward
Balances			(44.1)
Balances				(44.1)
Noncredit component of impairment losses on fixed maturities available-for-sale
Change in accumulated other comprehensive income (loss) rollforward
Balances				(44.1)
Noncredit component of impairment losses on fixed maturities available-for-sale | ASU 2016-13 - CECL | Effects of implementation of accounting change
Change in accumulated other comprehensive income (loss) rollforward
Balances			44.1
Balances				44.1
Net unrealized gains (losses) on derivative instruments
Change in accumulated other comprehensive income (loss) rollforward
Balances		51.8	18.2	53.4
Other comprehensive income (loss) during the period, net of adjustments		2.3	53.7	(13.2)
Amounts reclassified to accumulated other comprehensive income (loss)		(22.2)	(20.1)	(22.0)
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		(19.9)	33.6	(35.2)
Adjustment for reinsurance		7.4
Balances		39.3	51.8	18.2
Foreign currency translation adjustment
Change in accumulated other comprehensive income (loss) rollforward
Balances		(1,563.6)	(1,312.9)	(1,341.8)
Other comprehensive income (loss) during the period, net of adjustments		(23.7)	(270.0)	(7.3)
Amounts reclassified to accumulated other comprehensive income (loss)			19.3	36.2
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		(23.7)	(250.7)	28.9
Balances		(1,587.3)	(1,563.6)	(1,312.9)
Unrecognized postretirement benefit obligations
Change in accumulated other comprehensive income (loss) rollforward
Balances		(344.7)	(460.5)	(435.6)
Other comprehensive income (loss) during the period, net of adjustments		63.5	78.0	(67.0)
Amounts reclassified to accumulated other comprehensive income (loss)		27.1	37.8	42.1
Other comprehensive income (loss) attributable to Principal Financial Group, Inc.		90.6	115.8	(24.9)
Balances		$ (254.1)	$ (344.7)	$ (460.5)

[1] Excludes amounts attributable to redeemable noncontrolling interest. See Note 14, Stockholders’ Equity, for further details.