Investments (Schedule Of Increase (Decrease) In Payables For Collateral On Investments) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase (decrease) in payables for collateral on investments
Collateral payable for derivative investments	$ (129)	$ (493)	$ (286)
Securities pledged under securities lending agreements	6	(26)	38
Securities pledged under repurchase agreements	(5)	(138)	66
Investments pledged for FHLBI	(450)	995	430
Total increase (decrease) in payables for collateral on investments	$ (578)	$ 338	$ 248

- Definition

The net change during the reporting period in the amount of cash that is received related to collateral payable held for derivative instruments.

+ References

No definition available.

+ Details

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Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net change during the reporting period in the amount of cash that is received related to securities pledged under reverse repurchase agreements

+ References

No definition available.

+ Details

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Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net change during the reporting period in the amount of cash that is received related to securities pledged under securities lending agreements.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net change during the reporting period in the amount of cash that is received related to securities pledged for Federal Home Loan Bank of Indianapolis.

+ References

No definition available.

+ Details

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Balance Type:	debit
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- Definition

The increase (decrease) during the reporting period in the amount that is received as security when loaning securities.

+ References

No definition available.

+ Details

Name:	lnc_IncreaseDecreaseInCollateralForLoanedSecurities
Namespace Prefix:	lnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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