v3.26.1
Fair Value - Partnership's Financial Assets and Liabilities at Fair Value (Detail) - USD ($)
$ in Millions
Mar. 27, 2026
Dec. 31, 2025
Cash equivalents:    
Total cash equivalents $ 131 $ 202
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 7,968 9,471
Securities owned:    
Total investment securities 1,051 477
Inventory securities:    
Total inventory securities 48 54
Other Assets:    
Client Fractional Shares Ownership Assets 1,087 1,118
Accounts payable, accrued expenses and other:    
Client Fractional Shares Redemption Obligations 1,087 1,118
Equities [Member]    
Securities owned:    
Total investment securities 8 9
Inventory securities:    
Total inventory securities 10 17
Corporate Bonds and Notes [Member]    
Inventory securities:    
Total inventory securities 6 5
Government and Agency Obligations [Member]    
Securities owned:    
Total investment securities 699  
Inventory securities:    
Total inventory securities 2 1
U.S. Treasuries [Member]    
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 7,968 9,271
Mutual Funds [Member]    
Securities owned:    
Total investment securities [1] 344 393
Inventory securities:    
Total inventory securities 9 2
Municipal Obligations [Member]    
Inventory securities:    
Total inventory securities 17 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 4 6
Money Market Funds [Member]    
Cash equivalents:    
Total cash equivalents 36 107
Level I [Member]    
Cash equivalents:    
Total cash equivalents 36 107
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 7,968 9,271
Securities owned:    
Total investment securities 1,051 402
Inventory securities:    
Total inventory securities 21 20
Other Assets:    
Client Fractional Shares Ownership Assets 1,087 1,118
Accounts payable, accrued expenses and other:    
Client Fractional Shares Redemption Obligations 1,087 1,118
Level I [Member] | Equities [Member]    
Securities owned:    
Total investment securities 8 9
Inventory securities:    
Total inventory securities 10 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 699  
Inventory securities:    
Total inventory securities 2 1
Level I [Member] | U.S. Treasuries [Member]    
Investments segregated under federal regulations:    
Total investments segregated under federal regulations 7,968 9,271
Level I [Member] | Mutual Funds [Member]    
Securities owned:    
Total investment securities [1] 344 393
Inventory securities:    
Total inventory securities 9 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 36 107
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 27 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 6 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 17 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 4 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.