Receivables and Revenue - Schedule of Partnership's Disaggregated Revenue (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2024	Jun. 30, 2023	Jun. 28, 2024	Jun. 30, 2023
Disaggregation Of Revenue [Line Items]
Total revenue from customers	$ 3,631	$ 3,137	$ 7,155	$ 6,162
Net interest and dividends and other revenue	272	237	542	497
Net revenue	3,903	3,374	7,697	6,659
United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,540	3,057	6,976	6,005
Net interest and dividends and other revenue	253	222	505	464
Net revenue	3,793	3,279	7,481	6,469
Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	91	80	179	157
Net interest and dividends and other revenue	19	15	37	33
Net revenue	110	95	216	190
Total Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,198	2,792	6,298	5,477
Total Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,123	2,725	6,150	5,345
Total Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	75	67	148	132
Asset-based Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,011	2,600	5,919	5,101
Asset-based Fee Revenue [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	2,285	1,927	4,475	3,774
Asset-based Fee Revenue [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	400	368	792	729
Asset-based Fee Revenue [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	182	162	358	320
Asset-based Fee Revenue [Member] | Cash Solutions Fees Member
Disaggregation Of Revenue [Line Items]
Total revenue from customers	144	143	294	278
Asset-based Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	2,939	2,537	5,778	4,976
Asset-based Fee Revenue [Member] | United States [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	2,239	1,888	4,385	3,698
Asset-based Fee Revenue [Member] | United States [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	374	344	741	680
Asset-based Fee Revenue [Member] | United States [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	182	162	358	320
Asset-based Fee Revenue [Member] | United States [Member] | Cash Solutions Fees Member
Disaggregation Of Revenue [Line Items]
Total revenue from customers	144	143	294	278
Asset-based Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	72	63	141	125
Asset-based Fee Revenue [Member] | Canada [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	46	39	90	76
Asset-based Fee Revenue [Member] | Canada [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	26	24	51	49
Asset-based Fee Revenue [Member] | Canada [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	0	0	0	0
Asset-based Fee Revenue [Member] | Canada [Member] | Cash Solutions Fees Member
Disaggregation Of Revenue [Line Items]
Total revenue from customers	0	0	0	0
Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	187	192	379	376
Account and Activity Fee Revenue [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	117	115	233	230
Account and Activity Fee Revenue [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	70	77	146	146
Account and Activity Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	184	188	372	369
Account and Activity Fee Revenue [Member] | United States [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	117	115	233	230
Account and Activity Fee Revenue [Member] | United States [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	67	73	139	139
Account and Activity Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3	4	7	7
Account and Activity Fee Revenue [Member] | Canada [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	0	0	0	0
Account and Activity Fee Revenue [Member] | Canada [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3	4	7	7
Trade Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	433	345	857	685
Trade Revenue [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	376	294	746	582
Trade Revenue [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	57	51	111	103
Trade Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	417	332	826	660
Trade Revenue [Member] | United States [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	363	283	721	561
Trade Revenue [Member] | United States [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	54	49	105	99
Trade Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	16	13	31	25
Trade Revenue [Member] | Canada [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	13	11	25	21
Trade Revenue [Member] | Canada [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	$ 3	$ 2	$ 6	$ 4