Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Jan. 29, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	1-16725
Entity Registrant Name	PRINCIPAL FINANCIAL GROUP, INC
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	711 High Street
Entity Address, City or Town	Des Moines
Entity Address, State or Province	IA
Entity Address, Postal Zip Code	50392
Entity Tax Identification Number	42-1520346
City Area Code	515
Local Phone Number	247-5111
Title of 12(b) Security	Common Stock, par value $0.01
Trading Symbol	PFG
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		272,613,683
Entity Public Float			$ 11.4
Entity Central Index Key	0001126328
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false