Receivables and Revenue - Schedule of Partnership's Disaggregated Revenue (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 27, 2025	Jun. 28, 2024	Jun. 27, 2025	Jun. 28, 2024
Disaggregation Of Revenue [Line Items]
Total revenue from customers	$ 3,981	$ 3,631	$ 7,904	$ 7,155
Net interest and dividends and other revenue	254	272	498	542
Net revenue	4,235	3,903	8,402	7,697
United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,883	3,540	7,711	6,976
Net interest and dividends and other revenue	246	253	465	505
Net revenue	4,129	3,793	8,176	7,481
Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	98	91	193	179
Net interest and dividends and other revenue	8	19	33	37
Net revenue	106	110	226	216
Total Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,532	3,198	7,012	6,298
Total Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,448	3,123	6,850	6,150
Total Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	84	75	162	148
Asset-based Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,346	3,011	6,640	5,919
Asset-based Fee Revenue [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	2,605	2,285	5,150	4,475
Asset-based Fee Revenue [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	405	400	815	792
Asset-based Fee Revenue [Member] | Cash Solutions Fees Member
Disaggregation Of Revenue [Line Items]
Total revenue from customers	142	144	287	294
Asset-based Fee Revenue [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	194	182	388	358
Asset-based Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	3,266	2,939	6,485	5,778
Asset-based Fee Revenue [Member] | United States [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	2,551	2,239	5,047	4,385
Asset-based Fee Revenue [Member] | United States [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	379	374	763	741
Asset-based Fee Revenue [Member] | United States [Member] | Cash Solutions Fees Member
Disaggregation Of Revenue [Line Items]
Total revenue from customers	142	144	287	294
Asset-based Fee Revenue [Member] | United States [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	194	182	388	358
Asset-based Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	80	72	155	141
Asset-based Fee Revenue [Member] | Canada [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	54	46	103	90
Asset-based Fee Revenue [Member] | Canada [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	26	26	52	51
Asset-based Fee Revenue [Member] | Canada [Member] | Cash Solutions Fees Member
Disaggregation Of Revenue [Line Items]
Total revenue from customers	0	0	0	0
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
Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	186	187	372	379
Account and Activity Fee Revenue [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	115	117	233	233
Account and Activity Fee Revenue [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	71	70	139	146
Account and Activity Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	182	184	365	372
Account and Activity Fee Revenue [Member] | United States [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	115	117	233	233
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	67	132	139
Account and Activity Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	4	3	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	4	3	7	7
Trade Revenue [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	449	433	892	857
Trade Revenue [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	383	376	767	746
Trade Revenue [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	66	57	125	111
Trade Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	435	417	861	826
Trade Revenue [Member] | United States [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	371	363	741	721
Trade Revenue [Member] | United States [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	64	54	120	105
Trade Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	14	16	31	31
Trade Revenue [Member] | Canada [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	12	13	26	25
Trade Revenue [Member] | Canada [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Total revenue from customers	$ 2	$ 3	$ 5	$ 6