Investments (Composition Of Current And Past Due Mortgage Loans On Real Estate) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Mortgage Loans On Real Estate Aging [Abstract]
Current	$ 10,762	$ 9,888
Greater than 90 days past due	3	2
Valuation allowance associated with impaired mortgage loans on real estate	(3)	(2)	$ (2)	$ (3)
Unamortized premium (discount)		1
Total carrying value	$ 10,762	$ 9,889

No definition available.

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

- Definition

Mortgage loans on real estate that are current.

+ References

No definition available.

+ Details

Name:	lnc_MortgageLoansOnRealEstateCurrent
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Mortgage loans on real estate that are greater than 90 days past due.

+ References

No definition available.

+ Details

Name:	lnc_MortgageLoansOnRealEstateGreaterThanNinetyDaysPastDue
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of premium (net of discount) that was originally recognized at the issuance of the mortgage loan that has yet to be amortized.

+ References

No definition available.

+ Details

Name:	lnc_MortgageLoansOnRealEstateUnamortizedPremiumDiscount
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82921503&loc=d3e21338-158488

+ Details

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

- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(c))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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