Net Capital Requirements - Partnership's Net Capital Figures for U.S. and Canada Broker-Dealer Subsidiaries (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
United States [Member]
Regulatory Capital Requirements
Net capital	$ 991	$ 998
Net capital in excess of the minimum required	$ 846	$ 941
Net capital as a percentage of aggregate debit items	34.20%	35.00%
Net capital after anticipated capital withdrawals, as a percentage of aggregate debit items	22.40%	23.10%
Canada [Member]
Regulatory Capital Requirements
Regulatory risk adjusted capital	$ 29	$ 37
Regulatory risk adjusted capital in excess of the minimum required to be held by IIROC	$ 20	$ 33