Segment Information - Financial Information for Partnership's Reportable Segments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Revenues From External Customers And Long Lived Assets [Line Items]
Net revenue	$ 16,004	$ 13,798	$ 12,269
FA compensation	6,208	5,218	4,813
Home office operating expense	3,117	3,021	2,388
Branch office operating expenses	2,262	2,109	1,929
Variable compensation	2,436	1,838	1,735
Operating Expenses	14,023	12,186	10,865
Income before allocations	$ 1,981	$ 1,612	$ 1,404
Income before allocations margin	12.20%	11.40%	11.30%
Net interest and dividends revenue	$ 951	$ 885	$ 372
Depreciation and amortization	624	567	499
TOTAL ASSETS	28,964	28,003	29,892
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net revenue	15,561	13,409	11,902
FA compensation	6,035	5,069	4,665
Home office operating expense	3,019	2,927	2,312
Branch office operating expenses	2,195	2,046	1,868
Variable compensation	2,386	1,798	1,694
Operating Expenses	13,635	11,840	10,539
Income before allocations	$ 1,926	$ 1,569	$ 1,363
Income before allocations margin	12.20%	11.50%	11.30%
Net interest and dividends revenue	$ 906	$ 841	$ 354
Depreciation and amortization	608	552	483
TOTAL ASSETS	27,837	26,926	28,761
Canada [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Net revenue	443	389	367
FA compensation	173	149	148
Home office operating expense	98	94	76
Branch office operating expenses	67	63	61
Variable compensation	50	40	41
Operating Expenses	388	346	326
Income before allocations	$ 55	$ 43	$ 41
Income before allocations margin	12.30%	11.00%	11.00%
Net interest and dividends revenue	$ 45	$ 44	$ 18
Depreciation and amortization	16	15	16
TOTAL ASSETS	$ 1,127	$ 1,077	$ 1,131