Financing Receivable, Allowance for Credit Loss, Reasonable and Supportable Forecast Period

No definition available.

Name:	syf_FinancingReceivableAllowanceForCreditLossReasonableAndSupportableForecastPeriod
Namespace Prefix:	syf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable, Allowance for Credit Loss, Reversion Period

+ References

No definition available.

+ Details

Name:	syf_FinancingReceivableAllowanceForCreditLossReversionPeriod
Namespace Prefix:	syf_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable, Credit Quality Indicators, Percentage of Loan Receivables with No Vantage Score

+ References

No definition available.

+ Details

Name:	syf_FinancingReceivableCreditQualityIndicatorsPercentageOfLoanReceivablesWithNoVantageScore
Namespace Prefix:	syf_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Financing Receivable, Modification, Success Rate, Short-term

+ References

No definition available.

+ Details

Name:	syf_FinancingReceivableModificationSuccessRateShortTerm
Namespace Prefix:	syf_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable Modified Amount of Unpaid Balance Forgiven Short-term

+ References

No definition available.

+ Details

Name:	syf_FinancingReceivableModifiedAmountOfUnpaidBalanceForgivenShortTerm
Namespace Prefix:	syf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number Of Credit Score Categories

+ References

No definition available.

+ Details

Name:	syf_NumberOfCreditScoreCategories
Namespace Prefix:	syf_
Data Type:	xbrli:integerItemType
Balance Type:	na
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481628/310-20-40-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

+ Details

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

- Definition

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-11B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (1)
-Publisher SEC

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph a
-Subparagraph (3)
-Publisher SEC

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(7)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

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

- Definition

Percentage of decrease in weighted average contractual interest rate of financing receivable modified for debtor experiencing financial difficulty.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 12A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A

+ Details

Name:	us-gaap_FinancingReceivableModifiedWeightedAverageInterestRateDecreaseFromModification
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Unused amount of commitments to extend credit to customers.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CreditCardReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loan Receivables and Allowance for Credit Losses - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025 USD ($) creditScoreCategory	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) creditScoreCategory	Jun. 30, 2024 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Reasonable and supportable forecast period			12 months
Reversion period			6 months
Allowance for credit loss	$ 10,564	$ 10,982	$ 10,564	$ 10,982	$ 10,828	$ 10,929	$ 10,905	$ 10,571
Number of credit score categories \| creditScoreCategory	3		3
Percentage of loan receivables with no Vantage Score	0.30%	0.30%	0.30%	0.30%		0.30%
Financing receivable, modified, weighted average interest rate decrease from modification	97.00%	97.00%
Financing receivable modified percent of unpaid balance forgiven short-term	$ 13	$ 15
Modified loans success rate			63.00%	56.00%
Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit loss	9,906	10,255	$ 9,906	$ 10,255	10,133	$ 10,259	10,194	10,156
Unused commitments to extend credit	435,000		435,000			433,000
Consumer installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for credit loss	$ 545	$ 602	$ 545	$ 602	$ 584	$ 542	$ 581	$ 279