Receivable from Mutual Funds, Insurance Companies, and Other - Schedule of Partnership's Disaggregated Revenue (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation Of Revenue [Line Items]
Revenue	$ 11,984	$ 12,143	$ 9,894
Net interest and dividends and other revenue	285	136	169
Net revenue	12,269	12,279	10,063
United States [Member]
Disaggregation Of Revenue [Line Items]
Revenue	11,664	11,833	9,656
Net interest and dividends and other revenue	238	113	149
Net revenue	11,902	11,946	9,805
Canada [Member]
Disaggregation Of Revenue [Line Items]
Revenue	320	310	238
Net interest and dividends and other revenue	47	23	20
Net revenue	367	333	258
Total Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Revenue	10,500	10,424	8,175
Total Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Revenue	10,233	10,169	7,989
Total Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Revenue	267	255	186
Asset-based Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Revenue	9,808	9,737	7,515
Asset-based Fee Revenue [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	7,384	7,421	5,537
Asset-based Fee Revenue [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	1,512	1,676	1,387
Asset-based Fee Revenue [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	912	640	591
Asset-based Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Revenue	9,554	9,496	7,341
Asset-based Fee Revenue [Member] | United States [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	7,237	7,293	5,452
Asset-based Fee Revenue [Member] | United States [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	1,405	1,563	1,298
Asset-based Fee Revenue [Member] | United States [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	912	640	591
Asset-based Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Revenue	254	241	174
Asset-based Fee Revenue [Member] | Canada [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	147	128	85
Asset-based Fee Revenue [Member] | Canada [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	107	113	89
Asset-based Fee Revenue [Member] | Canada [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	0	0	0
Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Revenue	692	687	660
Account and Activity Fee Revenue [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	454	436	424
Account and Activity Fee Revenue [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Revenue	238	251	236
Account and Activity Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Revenue	679	673	648
Account and Activity Fee Revenue [Member] | United States [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	454	436	424
Account and Activity Fee Revenue [Member] | United States [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Revenue	225	237	224
Account and Activity Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Revenue	13	14	12
Account and Activity Fee Revenue [Member] | Canada [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Revenue	0	0	0
Account and Activity Fee Revenue [Member] | Canada [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Revenue	13	14	12
Trade Revenue [Member]
Disaggregation Of Revenue [Line Items]
Revenue	1,484	1,719	1,719
Trade Revenue [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	1,318	1,679	1,660
Trade Revenue [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	166	40	59
Trade Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Revenue	1,431	1,664	1,667
Trade Revenue [Member] | United States [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	1,273	1,627	1,611
Trade Revenue [Member] | United States [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	158	37	56
Trade Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Revenue	53	55	52
Trade Revenue [Member] | Canada [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	45	52	49
Trade Revenue [Member] | Canada [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	$ 8	$ 3	$ 3