Investments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014 item	Dec. 31, 2013 item	Dec. 31, 2012
Increase in gross AFS securities unrealized losses	$ (836)
Trading Securities, Unrealized Holding Loss	45	(172)	53
Number of partnerships in alternative investment portfolio	156	121
Investment commitments	1,400lnc_InvestmentCommitments
Investment commitments for limited partnerships	615
Investment commitments for private placements	388
Investment commitments for mortgage loans on real estate	372lnc_InvestmentCommitmentsMortgageLoans
Federal Home Loan Mortgage Corporation
Fair value	2,200	2,600
Concentration risk, percentage	2.00%	3.00%
Fannie Mae
Fair value	1,400	1,700
Concentration risk, percentage	1.00%	2.00%
Utilities Industry [Member]
Fair value	12,800	10,900
Concentration risk, percentage	13.00%	12.00%
Consumer Non-Cyclical Industry [Member]
Fair value	11,700	10,700
Concentration risk, percentage	11.00%	11.00%
Corporate bonds [Member]
Percentage of fair value rated as investment grade	96.00%	96.00%
Amortized cost of portfolio rated below investment grade	3,300	2,700
Fair value of portfolio rated below investment grade	3,200	2,700
Asset-backed Securities [Member]
Percentage of fair value rated as investment grade	88.00%	84.00%
Amortized cost of portfolio rated below investment grade	193	273
Fair value of portfolio rated below investment grade	$ 176	$ 226
Mortgage-backed securities [Member]
Projected default rate on existing delinquencies on MBS (low end of range)	10.00%	10.00%
Projected default rate on existing delinquencies on MBS (high end of range)	100.00%	100.00%
Severity of second lien loans	100.00%
Severity of first lien loans	30.00%
Mortgage loans on real estate [Member] \| California [Member]
Largest mortgage loan concentrations in geographic region	23.00%	23.00%
Mortgage loans on real estate [Member] \| Texas [Member]
Largest mortgage loan concentrations in geographic region	9.00%	9.00%

Amortized cost of portfolio rated below investment grade.

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- 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

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

+ References

No definition available.

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Fair value of portfolio rated below investment grade.

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No definition available.

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- 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.

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- Definition

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

+ References

No definition available.

+ Details

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

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No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

Largest concentration percentages of mortgage loans on commercial real estate throughout the U.S.

+ References

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- Definition

Number of partnerships represented in alternative investment portfolio.

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No definition available.

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- Definition

This item represents the default rate (as a percentage) of the underlying assets in the security that was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are other than temporarily impaired and the amount of such impairment determined to be related to credit loss recognized in earnings (high end of range).

+ References

No definition available.

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No definition available.

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- Definition

This item represents the loss severity as a percentage of first lien loans that was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are other than temporarily impaired and the amount of such impairment determined to be related to credit loss recognized in earnings.

+ References

No definition available.

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- Definition

This item represents the loss severity as a percentage of defaulted second lien loans that was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are other than temporarily impaired and the amount of such impairment determined to be related to credit loss recognized in earnings.

+ References

No definition available.

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- 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/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 21

-Subparagraph (a)

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-SubTopic 10

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- 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/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7

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- Definition

Amount of unrealized holding loss before gain recognized in the income statement for investments in trading securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7(c))

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-Name Accounting Standards Codification

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-SubTopic 10

-Section 35

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

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