Bank Loans and Related Allowance for Loan Losses (Convert to Amortizing Loans) (Details) - HELOCs [Member] $ in Millions	Mar. 31, 2018 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Converted to an amortizing loan by period end	$ 451
Within 1 year	495
1 year – 3 years	168
3 years – 5 years	145
5 years	537
Total	$ 1,796

Financing Receivable, Amount Converted to Amortizing Loan by Period End

No definition available.

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Namespace Prefix:	schw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financing Receivable, Converted to Amortizing Loan

+ References

No definition available.

+ Details

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Namespace Prefix:	schw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financing Receivable, Converted to Amortizing Loan, Year Five

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No definition available.

+ Details

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Namespace Prefix:	schw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financing Receivable, Converted to Amortizing Loan, Year One

+ References

No definition available.

+ Details

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Namespace Prefix:	schw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financing Receivable, Converted to Amortizing Loan, Year One to Year Three

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No definition available.

+ Details

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Namespace Prefix:	schw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financing Receivable, Converted to Amortizing Loan, Year Three to Year Five

+ References

No definition available.

+ Details

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Namespace Prefix:	schw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: