Fair Value - Partnership's Financial Assets and Liabilities at Fair Value (Detail) - USD ($) $ in Millions | Mar. 31, 2023 | Dec. 31, 2022 | Mar. 25, 2022 |
Cash equivalents: | | | |
Total cash equivalents | $ 349 | $ 193 | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 11,067 | 11,327 | $ 14,835 |
Investment securities: | | | |
Total investment securities | 823 | 1,329 | |
Inventory securities: | | | |
Total inventory securities | 75 | 76 | |
Other Assets | | | |
Client Fractional Shares Ownership Assets | 710 | 680 | |
Accounts payable, accrued expenses and other: | | | |
Client Fractional Shares Redemption Obligations | 710 | 680 | |
Equities [Member] | | | |
Investment securities: | | | |
Total investment securities | 8 | 8 | |
Inventory securities: | | | |
Total inventory securities | 29 | 20 | |
Corporate Bonds and Notes [Member] | | | |
Inventory securities: | | | |
Total inventory securities | 4 | 21 | |
Government and Agency Obligations [Member] | | | |
Investment securities: | | | |
Total investment securities | 400 | 1,000 | |
Inventory securities: | | | |
Total inventory securities | 1 | 3 | |
U.S. Treasuries [Member] | | | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 9,567 | 10,327 | |
Mutual Funds [Member] | | | |
Investment securities: | | | |
Total investment securities | 304 | 310 | |
Inventory securities: | | | |
Total inventory securities | 3 | 4 | |
Municipal Obligations [Member] | | | |
Investment securities: | | | |
Total investment securities | 11 | 11 | |
Inventory securities: | | | |
Total inventory securities | 33 | 28 | |
Certificates of Deposit [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 336 | 144 | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 1,500 | 1,000 | |
Investment securities: | | | |
Total investment securities | 100 | | |
Inventory securities: | | | |
Total inventory securities | 5 | | |
Money Market Fund [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 13 | 49 | |
Level I [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 13 | 49 | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 9,567 | 10,327 | |
Investment securities: | | | |
Total investment securities | 712 | 1,318 | |
Inventory securities: | | | |
Total inventory securities | 33 | 27 | |
Other Assets | | | |
Client Fractional Shares Ownership Assets | 710 | 680 | |
Accounts payable, accrued expenses and other: | | | |
Client Fractional Shares Redemption Obligations | 710 | 680 | |
Level I [Member] | Equities [Member] | | | |
Investment securities: | | | |
Total investment securities | 8 | 8 | |
Inventory securities: | | | |
Total inventory securities | 29 | 20 | |
Level I [Member] | Corporate Bonds and Notes [Member] | | | |
Inventory securities: | | | |
Total inventory securities | 0 | 0 | |
Level I [Member] | Government and Agency Obligations [Member] | | | |
Investment securities: | | | |
Total investment securities | 400 | 1,000 | |
Inventory securities: | | | |
Total inventory securities | 1 | 3 | |
Level I [Member] | U.S. Treasuries [Member] | | | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 9,567 | 10,327 | |
Level I [Member] | Mutual Funds [Member] | | | |
Investment securities: | | | |
Total investment securities | 304 | 310 | |
Inventory securities: | | | |
Total inventory securities | 3 | 4 | |
Level I [Member] | Municipal Obligations [Member] | | | |
Investment securities: | | | |
Total investment securities | 0 | 0 | |
Inventory securities: | | | |
Total inventory securities | 0 | 0 | |
Level I [Member] | Certificates of Deposit [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 0 | 0 | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 0 | 0 | |
Investment securities: | | | |
Total investment securities | 0 | | |
Inventory securities: | | | |
Total inventory securities | 0 | | |
Level I [Member] | Money Market Fund [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 13 | 49 | |
Level II [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 336 | 144 | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 1,500 | 1,000 | |
Investment securities: | | | |
Total investment securities | 111 | 11 | |
Inventory securities: | | | |
Total inventory securities | 42 | 49 | |
Other Assets | | | |
Client Fractional Shares Ownership Assets | 0 | 0 | |
Accounts payable, accrued expenses and other: | | | |
Client Fractional Shares Redemption Obligations | 0 | 0 | |
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] | | | |
Inventory securities: | | | |
Total inventory securities | 4 | 21 | |
Level II [Member] | Government and Agency Obligations [Member] | | | |
Investment securities: | | | |
Total investment securities | 0 | 0 | |
Inventory securities: | | | |
Total inventory 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] | Mutual Funds [Member] | | | |
Investment securities: | | | |
Total investment securities | 0 | 0 | |
Inventory securities: | | | |
Total inventory securities | 0 | 0 | |
Level II [Member] | Municipal Obligations [Member] | | | |
Investment securities: | | | |
Total investment securities | 11 | 11 | |
Inventory securities: | | | |
Total inventory securities | 33 | 28 | |
Level II [Member] | Certificates of Deposit [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 336 | 144 | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 1,500 | 1,000 | |
Investment securities: | | | |
Total investment securities | 100 | | |
Inventory securities: | | | |
Total inventory securities | 5 | | |
Level II [Member] | Money Market Fund [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 0 | 0 | |
Level III [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 0 | 0 | |
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 | |
Other Assets | | | |
Client Fractional Shares Ownership Assets | 0 | 0 | |
Accounts payable, accrued expenses and other: | | | |
Client Fractional Shares Redemption Obligations | 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] | | | |
Inventory securities: | | | |
Total inventory securities | 0 | 0 | |
Level III [Member] | Government and Agency Obligations [Member] | | | |
Investment securities: | | | |
Total investment securities | 0 | 0 | |
Inventory securities: | | | |
Total inventory 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] | Mutual Funds [Member] | | | |
Investment securities: | | | |
Total investment securities | 0 | 0 | |
Inventory securities: | | | |
Total inventory securities | 0 | 0 | |
Level III [Member] | Municipal Obligations [Member] | | | |
Investment securities: | | | |
Total investment securities | 0 | 0 | |
Inventory securities: | | | |
Total inventory securities | 0 | 0 | |
Level III [Member] | Certificates of Deposit [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | 0 | 0 | |
Investments segregated under federal regulations: | | | |
Total investments segregated under federal regulations | 0 | 0 | |
Investment securities: | | | |
Total investment securities | 0 | | |
Inventory securities: | | | |
Total inventory securities | 0 | | |
Level III [Member] | Money Market Fund [Member] | | | |
Cash equivalents: | | | |
Total cash equivalents | $ 0 | $ 0 | |