Receivables from and Payables to Brokerage Clients (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Margin loans, net of allowance for doubtful accounts	$ 18,331	$ 15,257
Other brokerage receivables	2,245	1,898
Receivables from brokerage clients — net	20,576	17,155
Payables
Interest-bearing payables	22,840	28,336
Non-interest-bearing payables	8,403	7,558
Payables to brokerage clients	$ 31,243	$ 35,894
California [Member] \| Geographic Concentration Risk [Member] \| Contract with Customer [Member]
Concentration Risk [Line Items]
Percent of client accounts	22.00%	23.00%

Interest-bearing payables to brokerage clients.

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Margin loans to brokerage clients, net of allowance for doubtful accounts.

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Noninterst-bearing payables to brokerage clients.

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Other receivables from brokerage clients.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592

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-Publisher FASB
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Amounts payable to customers at the balance sheet date. The term customers generally excludes other broker-dealers; persons who are principal officers, directors, and stockholders; and persons whose securities or funds are part of the regulatory net capital of the broker-dealer. Another broker-dealer's account can be classified as a customer if the account is carried as an omnibus account in compliance with certain regulations. The accounts of principal officers, directors and stockholders may be combined in the customer captions if they are not material and the combination is disclosed in the oath that is required to accompany the annual audited FOCUS Report.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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Amount due from customers for fees and charges arising from transactions related to the entity's brokerage activities and operations.

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