Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	$ 513	$ 593
Securities available for sale	42,448	33,965
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	1,084	822
Investments segregated and on deposit for regulatory purposes	3,210	3,791
Other securities owned	513	593
Securities available for sale	42,448	33,965
Total	47,255	39,171
Fair Value, Measurements, Recurring | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	218	8
Fair Value, Measurements, Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	866	814
Fair Value, Measurements, Recurring | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments segregated and on deposit for regulatory purposes	2,675	2,374
Securities available for sale	5,536	3,622
Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments segregated and on deposit for regulatory purposes	535	767
Securities available for sale	5,610	3,571
Fair Value, Measurements, Recurring | Schwab Funds money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	244	332
Fair Value, Measurements, Recurring | Equity and bond mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	183	183
Fair Value, Measurements, Recurring | State and municipal debt obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	55	46
Fair Value, Measurements, Recurring | Equity, U.S. Government and corporate debt, and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	31	32
Fair Value, Measurements, Recurring | U.S. agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	23,772	20,921
Fair Value, Measurements, Recurring | Non-agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	782	907
Fair Value, Measurements, Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	449	225
Fair Value, Measurements, Recurring | U.S. agency notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	350	1,800
Fair Value, Measurements, Recurring | U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments segregated and on deposit for regulatory purposes		650
Fair Value, Measurements, Recurring | Asset-backed and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	5,949	2,919
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	218	8
Other securities owned	428	527
Total	646	535
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	218	8
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Schwab Funds money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	244	332
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Equity and bond mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	183	183
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Equity, U.S. Government and corporate debt, and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	1	12
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	866	814
Investments segregated and on deposit for regulatory purposes	3,210	3,791
Other securities owned	85	66
Securities available for sale	42,448	33,965
Total	46,609	38,636
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	866	814
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments segregated and on deposit for regulatory purposes	2,675	2,374
Securities available for sale	5,536	3,622
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments segregated and on deposit for regulatory purposes	535	767
Securities available for sale	5,610	3,571
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | State and municipal debt obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	55	46
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Equity, U.S. Government and corporate debt, and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other securities owned	30	20
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	23,772	20,921
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Non-agency residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	782	907
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	449	225
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. agency notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	350	1,800
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments segregated and on deposit for regulatory purposes		650
Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Asset-backed and other securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 5,949	$ 2,919