Investments (Narrative) (Details) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2021 USD ($) security loan item	Dec. 31, 2020 USD ($) security loan item
Investments [Line Items]
Increase (decrease) in gross AFS securities unrealized losses	$ 202
Number of partnerships in alternative investment portfolio \| item	300	271
Alternative investments as a percentage of overall invested assets	2.00%	1.00%
Amortized cost	$ 107,459	$ 104,174
Fair Value	122,085	123,044
Fair value of collateral received that we are permitted to sell or re-pledge	23
Investment commitments	2,700
Investment commitments for limited partnerships	1,700
Investment commitments for mortgage loans on real estate	346
Investment commitments for private placements	$ 667
Minimum [Member]
Investments [Line Items]
Percentage of the fair value of securities obtained as collateral under reverse repurchase agreements	80.00%
Maximum [Member]
Investments [Line Items]
Percentage of the fair value of securities obtained as collateral under reverse repurchase agreements	95.00%
Federal Home Loan Mortgage Corporation [Member] \| Investments [Member]
Investments [Line Items]
Fair value	$ 1,100	1,200
Federal National Mortgage Association [Member] \| Investments [Member]
Investments [Line Items]
Fair value		1,000
Consumer Non-Cyclical Industry [Member] \| Investments [Member]
Investments [Line Items]
Fair value	20,100	20,300
Financial Service [Member] \| Investments [Member]
Investments [Line Items]
Fair value	$ 19,400	$ 19,600
Corporate Bonds [Member]
Investments [Line Items]
Percentage of fair value rated as investment grade	96.00%	96.00%
Corporate Bonds [Member] \| External Credit Rating, Non Investment Grade [Member]
Investments [Line Items]
Amortized cost	$ 3,900	$ 4,100
Fair Value	$ 4,100	$ 4,200
Federal National Mortgage Association [Member] \| Federal Home Loan Mortgage Corporation [Member] \| Investments [Member]
Investments [Line Items]
Concentration risk, percentage	1.00%	1.00%
Federal National Mortgage Association [Member] \| Federal National Mortgage Association [Member] \| Investments [Member]
Investments [Line Items]
Concentration risk, percentage	1.00%	1.00%
Federal National Mortgage Association [Member] \| Consumer Non-Cyclical Industry [Member] \| Investments [Member]
Investments [Line Items]
Concentration risk, percentage	13.00%	13.00%
Federal National Mortgage Association [Member] \| Financial Service [Member] \| Investments [Member]
Investments [Line Items]
Concentration risk, percentage	12.00%	13.00%
Commercial [Member]
Investments [Line Items]
Number of impaired loans \| security	6	4
Impaired financing receivable, principal balance	$ 1	$ 1
Commercial [Member] \| Federal National Mortgage Association [Member] \| Geographic Concentration Risk [Member] \| Mortgage Loans On Real Estate [Member] \| California [Member]
Investments [Line Items]
Concentration risk, percentage	26.00%	24.00%
Commercial [Member] \| Federal National Mortgage Association [Member] \| Geographic Concentration Risk [Member] \| Mortgage Loans On Real Estate [Member] \| Texas [Member]
Investments [Line Items]
Concentration risk, percentage	9.00%	10.00%
Residential [Member]
Investments [Line Items]
Number of loans past due \| loan	65	147
Number of impaired loans \| security	54	76
Impaired financing receivable, principal balance	$ 25	$ 34
Residential [Member] \| Federal National Mortgage Association [Member] \| Geographic Concentration Risk [Member] \| Mortgage Loans On Real Estate [Member] \| California [Member]
Investments [Line Items]
Concentration risk, percentage	23.00%	32.00%
Residential [Member] \| Federal National Mortgage Association [Member] \| Geographic Concentration Risk [Member] \| Mortgage Loans On Real Estate [Member] \| Florida [Member]
Investments [Line Items]
Concentration risk, percentage	16.00%	18.00%

Alternative investments as a percentage of overall invested assets.

No definition available.

Name:	lnc_AlternativeInvestmentsAsPercentageOfOverallInvestedAssets
Namespace Prefix:	lnc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the change in gross unrealized holding gain or loss on available-for-sale securities that has been included in accumulated other comprehensive income, a separate component of shareholders' equity, during the period.

+ References

No definition available.

+ Details

Name:	lnc_AvailableForSaleSecuritiesChangeInGrossUnrealizedHoldingGainLoss
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of the fair value of portfolio that was rated investment grade as of balance sheet date.

+ References

No definition available.

+ Details

Name:	lnc_AvailableForSaleSecuritiesFairValueDisclosurePercentInvestmentGrade
Namespace Prefix:	lnc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This item represents the percentage of the fair value of securities obtained as collateral under reverse repurchase agreements

+ References

No definition available.

+ Details

Name:	lnc_CollateralObtainedPercentOfFairValueReverseRepurchaseAgreements
Namespace Prefix:	lnc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Financing receivable, Number of loans past due

+ References

No definition available.

+ Details

Name:	lnc_FinancingReceivableNumberOfLoansPastDue
Namespace Prefix:	lnc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Impaired financing receivable, number of impaired loans

+ References

No definition available.

+ Details

Name:	lnc_ImpairedFinancingReceivableNumberOfImpairedLoans
Namespace Prefix:	lnc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents total investment commitments as of the balance sheet date for fixed maturity available-for-sale securities, limited partnerships, real estate and mortgage loans on real estate.

+ References

No definition available.

+ Details

Name:	lnc_InvestmentCommitments
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This item represents investment commitments as of the balance sheet date for limited partnerships.

+ References

No definition available.

+ Details

Name:	lnc_InvestmentCommitmentsLimitedPartnerships
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This item represents investment commitments as of the balance sheet date for private placements.

+ References

No definition available.

+ Details

Name:	lnc_InvestmentCommitmentsLimitedPrivatePlacements
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This item represents investment commitments as of the balance sheet date for mortgage loans.

+ References

No definition available.

+ Details

Name:	lnc_InvestmentCommitmentsMortgageLoans
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Investments [Line Items]

+ References

No definition available.

+ Details

Name:	lnc_InvestmentsLineItems
Namespace Prefix:	lnc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of partnerships represented in alternative investment portfolio.

+ References

No definition available.

+ Details

Name:	lnc_NumberOfPartnershipsInAlternativeInvestmentPortfolio
Namespace Prefix:	lnc_
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

+ Details

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

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124260329&loc=d3e26610-111562

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

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

- Definition

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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13531-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13537-108611

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents disclosure of all significant concentrations of credit risk or market risk arising from the subject financial instrument (as defined), whether from an individual counterparty or groups of counterparties.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13531-108611

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

+ Details

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

- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5212-111524

+ Details

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

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_FederalHomeLoanMortgageCorporationCertificatesAndObligationsFHLMCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=lnc_InvestedAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=lnc_ConsumerNonCyclicalIndustryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_FinancialServiceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CorporateBondSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ExternalCreditRatingByGroupingAxis=us-gaap_ExternalCreditRatingNonInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_FederalNationalMortgageAssociationCertificatesAndObligationsFNMAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_GeographicConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_MortgagesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_CA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_TX
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_FL
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: