Fair Value Hierarchy for Financial Instruments Not Recorded at Fair Value (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Carrying Amount
Assets:
Cash and cash equivalents	$ 7,439
Cash and investments segregated and on deposit for regulatory purposes	21,824
Receivables from brokers, dealers, and clearing organizations	607
Receivables from brokerage clients - net	11,909
Securities held to maturity	15,612	15,108
Loans to banking clients - net	10,102	9,812
Other assets	64
Total	67,557
Liabilities:
Deposits from banking clients	68,756
Payables to brokers, dealers, and clearing organizations	1,445
Payables to brokerage clients	34,761
Accrued expenses and other liabilities	546
Long-term debt	1,776	2,001
Total	107,284
Carrying Amount | Residential real estate mortgages
Assets:
Loans to banking clients - net	5,947
Carrying Amount | Home equity lines of credit
Assets:
Loans to banking clients - net	3,324
Carrying Amount | Personal loans secured by securities
Assets:
Loans to banking clients - net	807
Carrying Amount | Other
Assets:
Loans to banking clients - net	24
Carrying Amount | U.S. agency residential mortgage-backed securities
Assets:
Securities held to maturity	15,450
Carrying Amount | Other securities
Assets:
Securities held to maturity	162
Fair Value
Assets:
Cash and cash equivalents	7,439
Cash and investments segregated and on deposit for regulatory purposes	21,824
Receivables from brokers, dealers, and clearing organizations	607
Receivables from brokerage clients - net	11,909
Securities held to maturity	16,229	15,539
Loans to banking clients - net	10,174	9,671
Other assets	64
Total	68,246
Liabilities:
Deposits from banking clients	68,756
Payables to brokers, dealers, and clearing organizations	1,445
Payables to brokerage clients	34,761
Accrued expenses and other liabilities	546
Long-term debt	1,717	2,159
Total	107,225
Fair Value | Residential real estate mortgages
Assets:
Loans to banking clients - net	6,028
Fair Value | Home equity lines of credit
Assets:
Loans to banking clients - net	3,315
Fair Value | Personal loans secured by securities
Assets:
Loans to banking clients - net	807
Fair Value | Other
Assets:
Loans to banking clients - net	24
Fair Value | U.S. agency residential mortgage-backed securities
Assets:
Securities held to maturity	16,067
Fair Value | Other securities
Assets:
Securities held to maturity	162
Fair Value | Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	7,439
Cash and investments segregated and on deposit for regulatory purposes	21,824
Receivables from brokers, dealers, and clearing organizations	607
Receivables from brokerage clients - net	11,909
Securities held to maturity	16,229
Loans to banking clients - net	10,174
Other assets	64
Total	68,246
Liabilities:
Deposits from banking clients	68,756
Payables to brokers, dealers, and clearing organizations	1,445
Payables to brokerage clients	34,761
Accrued expenses and other liabilities	546
Long-term debt	1,717
Total	107,225
Fair Value | Significant Other Observable Inputs (Level 2) | Residential real estate mortgages
Assets:
Loans to banking clients - net	6,028
Fair Value | Significant Other Observable Inputs (Level 2) | Home equity lines of credit
Assets:
Loans to banking clients - net	3,315
Fair Value | Significant Other Observable Inputs (Level 2) | Personal loans secured by securities
Assets:
Loans to banking clients - net	807
Fair Value | Significant Other Observable Inputs (Level 2) | Other
Assets:
Loans to banking clients - net	24
Fair Value | Significant Other Observable Inputs (Level 2) | U.S. agency residential mortgage-backed securities
Assets:
Securities held to maturity	16,067
Fair Value | Significant Other Observable Inputs (Level 2) | Other securities
Assets:
Securities held to maturity	$ 162