Investments (Reconciliation Of Available-For-Sale Securities From Cost Basis To Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	$ 104,526	$ 103,021
Gross Unrealized Gains	13,431	18,287
Gross Unrealized Losses	427	184
Allowance for Credit Losses	19	13
Fair Value	117,511	121,111
Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	104,526
Fair Value	117,511
Corporate Bonds [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Allowance for Credit Losses	17	12
Corporate Bonds [Member] \| Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	86,197	85,625
Gross Unrealized Gains	11,569	15,947
Gross Unrealized Losses	326	136
Allowance for Credit Losses	17	12
Fair Value	97,423	101,424
ABS [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Allowance for Credit Losses	1
ABS [Member] \| Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	8,433	7,035
Gross Unrealized Gains	127	158
Gross Unrealized Losses	54	15
Fair Value	8,506	7,178
U.S. Government Bonds [Member] \| Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	348	369
Gross Unrealized Gains	54	81
Gross Unrealized Losses	2	1
Fair Value	400	449
Foreign Government Bonds [Member] \| Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	365	380
Gross Unrealized Gains	63	86
Gross Unrealized Losses	5	1
Fair Value	423	465
RMBS [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Allowance for Credit Losses	1	1
RMBS [Member] \| Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	2,132	2,551
Gross Unrealized Gains	178	289
Gross Unrealized Losses	4	1
Allowance for Credit Losses	1	1
Fair Value	2,305	2,838
CMBS [Member] \| Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	1,542	1,380
Gross Unrealized Gains	62	115
Gross Unrealized Losses	14
Fair Value	1,590	1,495
State And Municipal Bonds [Member] \| Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	5,113	5,145
Gross Unrealized Gains	1,275	1,517
Gross Unrealized Losses	11
Fair Value	6,377	6,662
Hybrid And Redeemable Preferred Securities [Member] \| Fixed Maturity AFS Securities [Member]
Amortized cost, gross unrealized gains, losses, OTTI and fair value of AFS securities
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	396	536
Gross Unrealized Gains	103	94
Gross Unrealized Losses	11	30
Allowance for Credit Losses	1
Fair Value	$ 487	$ 600

No definition available.

Name:	cik0000726865_AmortizedCostGrossUnrealizedGainsLossesOttiAndFairValueOfAfsSecuritiesAbstract
Namespace Prefix:	cik0000726865_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

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

- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Amount of allowance for credit loss on 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 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 4: 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_DebtSecuritiesAvailableForSaleAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Details

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

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=cik0000726865_HybridAndRedeemablePreferredSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: