Fair Value - Partnership's Financial Assets at Fair Value (Detail) - USD ($) $ in Millions | Jun. 26, 2015 | Dec. 31, 2014 | Jun. 27, 2014 | Dec. 31, 2013 |
Cash equivalents: | | | | |
Cash and cash equivalents | $ 1,040 | $ 1,033 | $ 536 | $ 600 |
Investments segregated under federal regulations: | | | | |
Total investments segregated under federal regulations | 2,457 | 1,334 | | |
Investment securities: | | | | |
Total investment securities | 211 | 161 | | |
Inventory securities: | | | | |
Total inventory securities | 98 | 69 | | |
Mutual Funds [Member] | | | | |
Investment securities: | | | | |
Total investment securities | 187 | 136 | | |
Inventory securities: | | | | |
Total inventory securities | 6 | 5 | | |
Government and Agency Obligations [Member] | | | | |
Investment securities: | | | | |
Total investment securities | 19 | 19 | | |
Other [Member] | | | | |
Inventory securities: | | | | |
Total inventory securities | | 2 | | |
U.S. Treasuries [Member] | | | | |
Investments segregated under federal regulations: | | | | |
Total investments segregated under federal regulations | 2,207 | 1,109 | | |
State and Municipal Obligations [Member] | | | | |
Inventory securities: | | | | |
Total inventory securities | 59 | 40 | | |
Equities [Member] | | | | |
Investment securities: | | | | |
Total investment securities | 4 | 5 | | |
Inventory securities: | | | | |
Total inventory securities | 28 | 17 | | |
Corporate Bonds and Notes [Member] | | | | |
Investment securities: | | | | |
Total investment securities | 1 | 1 | | |
Inventory securities: | | | | |
Total inventory securities | 3 | 2 | | |
Certificates of Deposit [Member] | | | | |
Cash equivalents: | | | | |
Cash and cash equivalents | 150 | 100 | | |
Investments segregated under federal regulations: | | | | |
Total investments segregated under federal regulations | 250 | 225 | | |
Inventory securities: | | | | |
Total inventory securities | 2 | 3 | | |
Level I [Member] | | | | |
Investments segregated under federal regulations: | | | | |
Total investments segregated under federal regulations | 2,207 | 1,109 | | |
Investment securities: | | | | |
Total investment securities | 210 | 160 | | |
Inventory securities: | | | | |
Total inventory securities | 34 | 23 | | |
Level I [Member] | Mutual Funds [Member] | | | | |
Investment securities: | | | | |
Total investment securities | 187 | 136 | | |
Inventory securities: | | | | |
Total inventory securities | 6 | 5 | | |
Level I [Member] | Government and Agency Obligations [Member] | | | | |
Investment securities: | | | | |
Total investment securities | 19 | 19 | | |
Level I [Member] | Other [Member] | | | | |
Inventory securities: | | | | |
Total inventory securities | | 1 | | |
Level I [Member] | U.S. Treasuries [Member] | | | | |
Investments segregated under federal regulations: | | | | |
Total investments segregated under federal regulations | 2,207 | 1,109 | | |
Level I [Member] | Equities [Member] | | | | |
Investment securities: | | | | |
Total investment securities | 4 | 5 | | |
Inventory securities: | | | | |
Total inventory securities | 28 | 17 | | |
Level II [Member] | | | | |
Investments segregated under federal regulations: | | | | |
Total investments segregated under federal regulations | 250 | 225 | | |
Investment securities: | | | | |
Total investment securities | 1 | 1 | | |
Inventory securities: | | | | |
Total inventory securities | 64 | 46 | | |
Level II [Member] | Other [Member] | | | | |
Inventory securities: | | | | |
Total inventory securities | | 1 | | |
Level II [Member] | State and Municipal Obligations [Member] | | | | |
Inventory securities: | | | | |
Total inventory securities | 59 | 40 | | |
Level II [Member] | Corporate Bonds and Notes [Member] | | | | |
Investment securities: | | | | |
Total investment securities | 1 | 1 | | |
Inventory securities: | | | | |
Total inventory securities | 3 | 2 | | |
Level II [Member] | Certificates of Deposit [Member] | | | | |
Cash equivalents: | | | | |
Cash and cash equivalents | 150 | 100 | | |
Investments segregated under federal regulations: | | | | |
Total investments segregated under federal regulations | 250 | 225 | | |
Inventory securities: | | | | |
Total inventory securities | $ 2 | $ 3 | | |