Segment Information - Financial Information for Partnership's Reportable Segments (Detail) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) Advisor	Sep. 25, 2020 USD ($)	Jun. 26, 2020 USD ($)	Mar. 27, 2020 USD ($)	Dec. 31, 2019 USD ($) Advisor	Sep. 27, 2019 USD ($)	Jun. 28, 2019 USD ($)	Mar. 29, 2019 USD ($)	Dec. 31, 2020 USD ($) Advisor	Dec. 31, 2019 USD ($) Advisor	Dec. 31, 2018 USD ($) Advisor
Net revenue:
Total net revenue	$ 2,720	$ 2,527	$ 2,325	$ 2,491	$ 2,493	$ 2,367	$ 2,319	$ 2,190	$ 10,063	$ 9,369	$ 8,469
Net interest and dividends revenue:
Total net interest and dividends revenue									105	259	237
Pre-variable income:
Total pre-variable income									2,699	2,210	1,988
Variable compensation:
Total variable compensation									1,414	1,118	998
Income (loss) before allocations to partners:
Total income before allocations to partners	378	$ 316	$ 288	$ 303	285	$ 281	$ 285	$ 241	1,285	1,092	990
Capital expenditures:
Total capital expenditures									129	176	105
Depreciation and amortization:
Depreciation and amortization									125	115	94
Total assets at year end:
Total assets	$ 28,320				$ 19,317				$ 28,320	$ 19,317	$ 15,815
Financial advisors at year end:
Total financial advisors | Advisor	19,225				18,704				19,225	18,704	17,615
United States [Member]
Net revenue:
Total net revenue									$ 9,805	$ 9,127	$ 8,233
Net interest and dividends revenue:
Total net interest and dividends revenue									99	249	228
Pre-variable income:
Total pre-variable income									2,673	2,194	1,972
Variable compensation:
Total variable compensation									1,385	1,094	975
Income (loss) before allocations to partners:
Total income before allocations to partners									1,288	1,100	997
Capital expenditures:
Total capital expenditures									126	170	102
Depreciation and amortization:
Depreciation and amortization									123	113	92
Total assets at year end:
Total assets	$ 27,258				$ 18,577				$ 27,258	$ 18,577	$ 15,187
Financial advisors at year end:
Total financial advisors | Advisor	18,321				17,830				18,321	17,830	16,797
Canada [Member]
Net revenue:
Total net revenue									$ 258	$ 242	$ 236
Net interest and dividends revenue:
Total net interest and dividends revenue									6	10	9
Pre-variable income:
Total pre-variable income									26	16	16
Variable compensation:
Total variable compensation									29	24	23
Income (loss) before allocations to partners:
Total income before allocations to partners									(3)	(8)	(7)
Capital expenditures:
Total capital expenditures									3	6	3
Depreciation and amortization:
Depreciation and amortization									2	2	2
Total assets at year end:
Total assets	$ 1,062				$ 740				$ 1,062	$ 740	$ 628
Financial advisors at year end:
Total financial advisors | Advisor	904				874				904	874	818