Financing Receivables - Credit Quality Information - Financial Advisor Loans (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Financing receivables - credit quality information
Allowance for credit losses	$ 64	$ 57	$ 59	$ 50
Loan write-offs	3	1
Commercial Loans
Financing receivables - credit quality information
Allowance for credit losses	56	53	54	$ 47
Loan write-offs	2	$ 0
Commercial Loans | Loans to financial advisors
Financing receivables - credit quality information
Loan write-offs	0
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	327		359
Year 2	325		179
Year 3	158		134
Year 4	116		101
Year 5	88		77
Prior	180		163
Total amortized cost basis	1,194		1,013
Commercial Loans | Loans to financial advisors | Active
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	327		359
Year 2	325		178
Year 3	157		133
Year 4	114		99
Year 5	84		76
Prior	175		158
Total amortized cost basis	1,182		1,003
Commercial Loans | Loans to financial advisors | Terminated
Financing receivables - credit quality information
Allowance for credit losses	7		6
Amortized cost basis by year of origination and loan-to-value ratio
Year 1	0		0
Year 2	0		1
Year 3	1		1
Year 4	2		2
Year 5	4		1
Prior	5		5
Total amortized cost basis	$ 12		$ 10