SEGMENT INFORMATION, Information Concerning Operations (Details) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment			5
Revenues:
Net revenues	$ 2,068	$ 1,859	$ 4,077	$ 3,790
Pre-tax income
Pre-tax income	239	347	598	679
Net interest income (expense):
Net interest income	242	249	488	492
Total assets:
Total assets	49,809		49,809		$ 38,830
Goodwill:
Goodwill	463		463		464
Operating segments | Private Client Group
Revenues:
Net revenues	1,495	1,271	2,909	2,627
Pre-tax income
Pre-tax income	170	132	323	296
Net interest income (expense):
Net interest income	38	47	79	93
Total assets:
Total assets	12,531		12,531		9,042
Goodwill:
Goodwill	274		274		275
Operating segments | Capital Markets
Revenues:
Net revenues	290	277	558	530
Pre-tax income
Pre-tax income	28	41	57	53
Net interest income (expense):
Net interest income	4	1	6	3
Total assets:
Total assets	2,118		2,118		2,287
Goodwill:
Goodwill	120		120		120
Operating segments | Asset Management
Revenues:
Net revenues	184	162	368	336
Pre-tax income
Pre-tax income	73	55	146	119
Net interest income (expense):
Net interest income	0	1	1	2
Total assets:
Total assets	348		348		401
Goodwill:
Goodwill	69		69		69
Operating segments | RJ Bank
Revenues:
Net revenues	210	212	426	415
Pre-tax income
Pre-tax income	14	136	149	246
Net interest income (expense):
Net interest income	205	205	415	402
Total assets:
Total assets	33,434		33,434		25,516
Operating segments | Other
Revenues:
Net revenues	(44)	0	(52)	2
Pre-tax income
Pre-tax income	(46)	(17)	(77)	(35)
Total assets:
Total assets	1,378		1,378		$ 1,584
Intersegment eliminations
Revenues:
Net revenues	(67)	(63)	(132)	(120)
Other and intersegment eliminations | Other
Revenues:
Net revenues	(111)	(63)	(184)	(118)
Net interest income (expense):
Net interest income	$ (5)	$ (5)	$ (13)	$ (8)