Financial Instruments Subject to Off-Balance Sheet Credit Risk (Summary of the Fair Value of Client Securities Available to Utilize as Collateral and Amounts Pledged) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Securities Financing Transaction [Line Items]
Fair value of client securities available to be pledged	$ 25,905	$ 21,516
Fair value of client securities pledged	5,075	5,193
Fulfillment of Requirements with the Options Clearing Corporation [Member]
Securities Financing Transaction [Line Items]
Fair value of client securities pledged	2,280	1,519
Fulfillment of Client Short Sales [Member]
Securities Financing Transaction [Line Items]
Fair value of client securities pledged	2,011	2,048
Securities Lending to Other Broker-Dealers [Member]
Securities Financing Transaction [Line Items]
Fair value of client securities pledged	784	1,626
Fully-Paid Client Securities [Member]
Securities Financing Transaction [Line Items]
Fair value of client securities pledged	$ 78	$ 58

Fair value of collateral permitted, by contact or custom, to be sold or re-pledged.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

+ Details

Name:	us-gaap_FairValueOfSecuritiesReceivedAsCollateralThatCanBeResoldOrRepledged
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of the collateral, or portion thereof, that has been re-pledged, delivered, or otherwise used.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

+ Details

Name:	us-gaap_FairValueOfSecuritiesReceivedAsCollateralThatHaveBeenResoldOrRepledged
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_SecuritiesFinancingTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SecuritiesFinancingTransactionAxis=schw_FulfillmentofRequirementswithOptionsClearingCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SecuritiesFinancingTransactionAxis=schw_FulfillmentofClientShortSalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SecuritiesFinancingTransactionAxis=schw_SecuritiesLendingtoOtherBrokerDealersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SecuritiesFinancingTransactionAxis=schw_FullyPaidClientSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: