Fair Value - Partnership's Financial Assets at Fair Value (Detail) - USD ($) $ in Millions	Mar. 25, 2016	Dec. 31, 2015
Investments segregated under federal regulations:
Total investments segregated under federal regulations	$ 2,905	$ 3,006
Investment securities:
Total investment securities	197	201
Inventory securities:
Total inventory securities	57	36
Equities [Member]
Investment securities:
Total investment securities	5	4
Inventory securities:
Total inventory securities	10	17
Corporate Bonds and Notes [Member]
Investment securities:
Total investment securities	1	1
Inventory securities:
Total inventory securities	2	1
Mutual Funds [Member]
Investment securities:
Total investment securities	187	192
Inventory securities:
Total inventory securities	5	7
Government and Agency Obligations [Member]
Investment securities:
Total investment securities	4	4
U.S. Treasuries [Member]
Investments segregated under federal regulations:
Total investments segregated under federal regulations	2,605	2,706
State and Municipal Obligations [Member]
Inventory securities:
Total inventory securities	37	11
Level I [Member]
Investments segregated under federal regulations:
Total investments segregated under federal regulations	2,605	2,706
Investment securities:
Total investment securities	196	200
Inventory securities:
Total inventory securities	15	24
Level I [Member] | Equities [Member]
Investment securities:
Total investment securities	5	4
Inventory securities:
Total inventory securities	10	17
Level I [Member] | Corporate Bonds and Notes [Member]
Investment securities:
Total investment securities	0	0
Inventory securities:
Total inventory securities	0	0
Level I [Member] | Mutual Funds [Member]
Investment securities:
Total investment securities	187	192
Inventory securities:
Total inventory securities	5	7
Level I [Member] | Government and Agency Obligations [Member]
Investment securities:
Total investment securities	4	4
Level I [Member] | U.S. Treasuries [Member]
Investments segregated under federal regulations:
Total investments segregated under federal regulations	2,605	2,706
Level I [Member] | State and Municipal Obligations [Member]
Inventory securities:
Total inventory securities	0	0
Level II [Member]
Investments segregated under federal regulations:
Total investments segregated under federal regulations	300	300
Investment securities:
Total investment securities	1	1
Inventory securities:
Total inventory securities	42	12
Level II [Member] | Equities [Member]
Investment securities:
Total investment securities	0	0
Inventory securities:
Total inventory securities	0	0
Level II [Member] | Corporate Bonds and Notes [Member]
Investment securities:
Total investment securities	1	1
Inventory securities:
Total inventory securities	2	1
Level II [Member] | Mutual Funds [Member]
Investment securities:
Total investment securities	0	0
Inventory securities:
Total inventory securities	0	0
Level II [Member] | Government and Agency Obligations [Member]
Investment securities:
Total investment securities	0	0
Level II [Member] | U.S. Treasuries [Member]
Investments segregated under federal regulations:
Total investments segregated under federal regulations	0	0
Level II [Member] | State and Municipal Obligations [Member]
Inventory securities:
Total inventory securities	37	11
Level III [Member]
Investments segregated under federal regulations:
Total investments segregated under federal regulations	0	0
Investment securities:
Total investment securities	0	0
Inventory securities:
Total inventory securities	0	0
Level III [Member] | Equities [Member]
Investment securities:
Total investment securities	0	0
Inventory securities:
Total inventory securities	0	0
Level III [Member] | Corporate Bonds and Notes [Member]
Investment securities:
Total investment securities	0	0
Inventory securities:
Total inventory securities	0	0
Level III [Member] | Mutual Funds [Member]
Investment securities:
Total investment securities	0	0
Inventory securities:
Total inventory securities	0	0
Level III [Member] | Government and Agency Obligations [Member]
Investment securities:
Total investment securities	0	0
Level III [Member] | U.S. Treasuries [Member]
Investments segregated under federal regulations:
Total investments segregated under federal regulations	0	0
Level III [Member] | State and Municipal Obligations [Member]
Inventory securities:
Total inventory securities	0	0
Certificates of Deposit [Member]
Cash equivalents:
Cash and cash equivalents	150	150
Investments segregated under federal regulations:
Total investments segregated under federal regulations	300	300
Inventory securities:
Total inventory securities	3
Certificates of Deposit [Member] | Level I [Member]
Cash equivalents:
Cash and cash equivalents	0	0
Investments segregated under federal regulations:
Total investments segregated under federal regulations	0	0
Inventory securities:
Total inventory securities	0
Certificates of Deposit [Member] | Level II [Member]
Cash equivalents:
Cash and cash equivalents	150	150
Investments segregated under federal regulations:
Total investments segregated under federal regulations	300	300
Inventory securities:
Total inventory securities	3
Certificates of Deposit [Member] | Level III [Member]
Cash equivalents:
Cash and cash equivalents	0	0
Investments segregated under federal regulations:
Total investments segregated under federal regulations	0	$ 0
Inventory securities:
Total inventory securities	$ 0