Segment Information - Financial Information for Partnership's Reportable Segments (Detail) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($) Advisor	Sep. 29, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) Advisor	Sep. 30, 2016 USD ($)	Jun. 24, 2016 USD ($)	Mar. 25, 2016 USD ($)	Dec. 31, 2017 USD ($) Advisor	Dec. 31, 2016 USD ($) Advisor	Dec. 31, 2015 USD ($) Advisor
Net revenue:
Total net revenue	$ 1,975	$ 1,852	$ 1,882	$ 1,797	$ 1,653	$ 1,683	$ 1,660	$ 1,561	$ 7,506	$ 6,557	$ 6,619
Net interest and dividends revenue:
Total net interest and dividends revenue									174	118	83
Pre-variable income (loss):
Total pre-variable income									1,685	1,418	1,658
Variable compensation:
Total variable compensation									813	672	820
Income (loss) before allocations to partners:
Total income before allocations to partners	239	$ 211	$ 225	$ 197	161	$ 186	$ 208	$ 191	872	746	838
Capital expenditures:
Total capital expenditures									80	73	94
Depreciation and amortization:
Depreciation and amortization									85	82	83
Total assets at year end:
Total assets	$ 17,176				$ 19,424				$ 17,176	$ 19,424	$ 16,356
Financial advisors at year end:
Total financial advisors | Advisor	16,095				14,919				16,095	14,919	14,508
United States [Member]
Net revenue:
Total net revenue									$ 7,305	$ 6,381	$ 6,432
Net interest and dividends revenue:
Total net interest and dividends revenue									170	116	81
Pre-variable income (loss):
Total pre-variable income									1,681	1,417	1,650
Variable compensation:
Total variable compensation									795	657	803
Income (loss) before allocations to partners:
Total income before allocations to partners									886	760	847
Capital expenditures:
Total capital expenditures									78	72	93
Depreciation and amortization:
Depreciation and amortization									83	80	81
Total assets at year end:
Total assets	$ 16,563				$ 18,850				$ 16,563	$ 18,850	$ 15,897
Financial advisors at year end:
Total financial advisors | Advisor	15,347				14,259				15,347	14,259	13,839
Canada [Member]
Net revenue:
Total net revenue									$ 201	$ 176	$ 187
Net interest and dividends revenue:
Total net interest and dividends revenue									4	2	2
Pre-variable income (loss):
Total pre-variable income									4	1	8
Variable compensation:
Total variable compensation									18	15	17
Income (loss) before allocations to partners:
Total income before allocations to partners									(14)	(14)	(9)
Capital expenditures:
Total capital expenditures									2	1	1
Depreciation and amortization:
Depreciation and amortization									2	2	2
Total assets at year end:
Total assets	$ 613				$ 574				$ 613	$ 574	$ 459
Financial advisors at year end:
Total financial advisors | Advisor	748				660				748	660	669