Investments (Credit Quality Indicators For Commercial Mortgage Loans) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	$ 16,152	$ 15,606
Percent of total	100.00%	100.00%
Loan-to-value ratio, less than 65% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	$ 14,723	$ 14,206
Percent of total	91.20%	91.00%
Debt-service coverage ratio	2.40	2.35
Loan-to-value ratio, less than 65% [Member] \| Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	$ 14,723
Loan-to-value ratio, 65% to 74% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	$ 1,428	$ 1,399
Percent of total	8.80%	9.00%
Debt-service coverage ratio	1.85	1.87
Loan-to-value ratio, 65% to 74% [Member] \| Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	$ 1,428
Loan-to-value ratio, 75% to 100% [Member] \| Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Amortized Cost	$ 1	$ 1
Percent of total	0.00%	0.00%
Debt-service coverage ratio	0.90	1.09

Ratio that compares a property's net operating income to its debt-service payments.

No definition available.

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- Definition

Reflects the percentage derived from dividing mortgage loans with a specified loan-to-value ratio by total principal amount of mortgage loans.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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

No definition available.

+ Details

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Period Type:	duration

- Definition

Amount, before allowance for credit loss, of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447

+ Details

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Balance Type:	debit
Period Type:	instant

- Details

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- Details

Name:	us-gaap_LoanToValueAxis=lnc_LoanToValueRatioLessThanSixtyFiveMember
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- Details

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- Details

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