Receivables and Revenue - Schedule of Partnership's Disaggregated Revenue (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 24, 2021	Sep. 25, 2020	Sep. 24, 2021	Sep. 25, 2020
Disaggregation Of Revenue [Line Items]
Net revenue	$ 3,109	$ 2,487	$ 8,923	$ 7,230
Net interest and dividends and other revenue	31	40	104	113
Net revenue	3,140	2,527	9,027	7,343
United States [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	3,030	2,429	8,696	7,055
Net interest and dividends and other revenue	22	40	89	98
Net revenue	3,052	2,469	8,785	7,153
Canada [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	79	58	227	175
Net interest and dividends and other revenue	9	0	15	15
Net revenue	88	58	242	190
Asset-based Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	2,535	1,926	7,129	5,450
Asset-based Fee Revenue [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	1,938	1,431	5,418	3,989
Asset-based Fee Revenue [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	432	353	1,240	1,016
Asset-based Fee Revenue [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	165	142	471	445
Asset-based Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	2,472	1,881	6,954	5,323
Asset-based Fee Revenue [Member] | United States [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	1,904	1,409	5,326	3,928
Asset-based Fee Revenue [Member] | United States [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	403	330	1,157	950
Asset-based Fee Revenue [Member] | United States [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	165	142	471	445
Asset-based Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	63	45	175	127
Asset-based Fee Revenue [Member] | Canada [Member] | Advisory Programs Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	34	22	92	61
Asset-based Fee Revenue [Member] | Canada [Member] | Service Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	29	23	83	66
Asset-based Fee Revenue [Member] | Canada [Member] | Other Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	0	0	0	0
Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	172	163	513	494
Account and Activity Fee Revenue [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	109	106	325	319
Account and Activity Fee Revenue [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	63	57	188	175
Account and Activity Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	168	160	502	485
Account and Activity Fee Revenue [Member] | United States [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	109	106	325	319
Account and Activity Fee Revenue [Member] | United States [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	59	54	177	166
Account and Activity Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	4	3	11	9
Account and Activity Fee Revenue [Member] | Canada [Member] | Shareholder Accounting Services Fees [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	0	0	0	0
Account and Activity Fee Revenue [Member] | Canada [Member] | Other Account and Activity Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	4	3	11	9
Total Fee Revenue [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	2,707	2,089	7,642	5,944
Total Fee Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	2,640	2,041	7,456	5,808
Total Fee Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	67	48	186	136
Trade Revenue [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	402	398	1,281	1,286
Trade Revenue [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	392	386	1,251	1,241
Trade Revenue [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	10	12	30	45
Trade Revenue [Member] | United States [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	390	388	1,240	1,247
Trade Revenue [Member] | United States [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	381	376	1,212	1,204
Trade Revenue [Member] | United States [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	9	12	28	43
Trade Revenue [Member] | Canada [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	12	10	41	39
Trade Revenue [Member] | Canada [Member] | Commissions [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	11	10	39	37
Trade Revenue [Member] | Canada [Member] | Principal Transactions [Member]
Disaggregation Of Revenue [Line Items]
Net revenue	$ 1	$ 0	$ 2	$ 2