v3.26.3
Fair Value - Partnership's Financial Assets and Liabilities at Fair Value (Detail) - USD ($)
$ in Millions
Sep. 25, 2026
Dec. 31, 2025
Cash equivalents:    
Total cash equivalents $ 206 $ 202
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 5,737 9,471
Securities owned:    
Total investment securities 801 477
Inventory securities:    
Total inventory securities 81 54
Other Assets:    
Client Fractional Shares Ownership Assets 1,236 1,118
Accounts payable, accrued expenses and other:    
Client Fractional Shares Redemption Obligations 1,236 1,118
Equities [Member]    
Securities owned:    
Total investment securities 9 9
Inventory securities:    
Total inventory securities 9 17
Corporate Bonds and Notes [Member]    
Inventory securities:    
Total inventory securities 8 5
Government and Agency Obligations [Member]    
Securities owned:    
Total investment securities 400  
Inventory securities:    
Total inventory securities 1 1
U.S. Treasuries [Member]    
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 5,737 9,271
Mutual Funds [Member]    
Securities owned:    
Total investment securities [1] 392 393
Inventory securities:    
Total inventory securities 11 2
Municipal Obligations [Member]    
Inventory securities:    
Total inventory securities 33 23
Certificates of deposit [Member]    
Cash equivalents:    
Total cash equivalents 95 95
Investments segregated under federal regulations:    
Total investments segregated under federal regulations   200
Securities owned:    
Total investment securities   75
Inventory securities:    
Total inventory securities 19 6
Money Market Funds [Member]    
Cash equivalents:    
Total cash equivalents 111 107
Level I [Member]    
Cash equivalents:    
Total cash equivalents 111 107
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 5,737 9,271
Securities owned:    
Total investment securities 801 402
Inventory securities:    
Total inventory securities 21 20
Other Assets:    
Client Fractional Shares Ownership Assets 1,236 1,118
Accounts payable, accrued expenses and other:    
Client Fractional Shares Redemption Obligations 1,236 1,118
Level I [Member] | Equities [Member]    
Securities owned:    
Total investment securities 9 9
Inventory securities:    
Total inventory securities 9 17
Level I [Member] | Corporate Bonds and Notes [Member]    
Inventory securities:    
Total inventory securities 0 0
Level I [Member] | Government and Agency Obligations [Member]    
Securities owned:    
Total investment securities 400  
Inventory securities:    
Total inventory securities 1 1
Level I [Member] | U.S. Treasuries [Member]    
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 5,737 9,271
Level I [Member] | Mutual Funds [Member]    
Securities owned:    
Total investment securities [1] 392 393
Inventory securities:    
Total inventory securities 11 2
Level I [Member] | Municipal Obligations [Member]    
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
Securities owned:    
Total investment securities   0
Inventory securities:    
Total inventory securities 0 0
Level I [Member] | Money Market Funds [Member]    
Cash equivalents:    
Total cash equivalents 111 107
Level II [Member]    
Cash equivalents:    
Total cash equivalents 95 95
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 0 200
Securities owned:    
Total investment securities 0 75
Inventory securities:    
Total inventory securities 60 34
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]    
Securities owned:    
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 8 5
Level II [Member] | Government and Agency Obligations [Member]    
Securities owned:    
Total investment securities 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]    
Securities owned:    
Total investment securities [1] 0 0
Inventory securities:    
Total inventory securities 0 0
Level II [Member] | Municipal Obligations [Member]    
Inventory securities:    
Total inventory securities 33 23
Level II [Member] | Certificates of deposit [Member]    
Cash equivalents:    
Total cash equivalents 95 95
Investments segregated under federal regulations:    
Total investments segregated under federal regulations   200
Securities owned:    
Total investment securities   75
Inventory securities:    
Total inventory securities 19 6
Level II [Member] | Money Market Funds [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
Securities owned:    
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]    
Securities owned:    
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]    
Securities owned:    
Total investment securities 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]    
Securities owned:    
Total investment securities [1] 0 0
Inventory securities:    
Total inventory securities 0 0
Level III [Member] | Municipal Obligations [Member]    
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
Securities owned:    
Total investment securities   0
Inventory securities:    
Total inventory securities 0 0
Level III [Member] | Money Market Funds [Member]    
Cash equivalents:    
Total cash equivalents $ 0 $ 0
[1] The mutual funds balance consists primarily of securities held to economically hedge future liabilities for the non-qualified deferred compensation plan. The balance also includes a security held for regulatory purposes at the Trust Co.