Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 26, 2021	Jun. 26, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	JONES FINANCIAL COMPANIES LLLP
Entity Central Index Key	0000815917
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity File Number	0-16633
Entity Tax Identification Number	43-1450818
Entity Address, Address Line One	12555 Manchester Road
Entity Address, City or Town	Des Peres
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63131
City Area Code	314
Local Phone Number	515-2000
Entity Incorporation, State or Country Code	MO
Entity Limited Partnership Interests Outstanding		1,237,109
Entity Interactive Data Current	Yes
Entity Public Float			$ 0
ICFR Auditor Attestation Flag	true
Document Annual Report	true
Document Transition Report	false