Estimated fair value of invested assets transferred from affiliates.

No definition available.

Name:	mlic_AssetsTransferredFromAffiliatesEstimatedFairValue
Namespace Prefix:	mlic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Estimated fair value of assets transfered to affiliates.

+ References

No definition available.

+ Details

Name:	mlic_AssetsTransferredToAffiliatesEstimatedFairValue
Namespace Prefix:	mlic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

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

- Definition

Description of the frequency of periodic payments (monthly, quarterly, annual).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentFrequencyOfPeriodicPayment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the sum of all other revenue and income realized from sales and other transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionSellingGeneralAndAdministrativeExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=us-gaap_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mlic_AmericanLifeInsuranceCompanyAlicoAndDelawareAmericanLifeInsuranceDelamMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mlic_ExeterReassuranceCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_AffiliatedEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Investments (Related Party Investment Transactions - Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party				$ 1,300,000,000
Related party investment administrative services		179,000,000	172,000,000	158,000,000
Related party net investment income		4,000,000	0	4,000,000
Exeter Reassurance Company [Member] \| Other Investments [Member]
Related Party Transaction [Line Items]
Carrying value of related party loans			75,000,000
Related party net investment income		5,000,000	5,000,000	5,000,000
Debt Instrument, Maturity Date		Dec. 30, 2014
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Assets Transferred To Affiliates, Estimated Fair Value		97,000,000	781,000,000	4,000,000
Assets Transferred From Affiliates, Estimated Fair Value	437,000,000	882,000,000	882,000,000	0
Debt Instrument, Frequency of Periodic Payment		semiannually
Debt Instrument, Face Amount	400,000,000	400,000,000
Affiliated Entity [Member] \| Related Party Loan One [Member]
Related Party Transaction [Line Items]
Debt Instrument, Frequency of Periodic Payment		semiannually
Debt Instrument, Maturity Date		Jul. 15, 2021
Debt Instrument, Face Amount	295,000,000	295,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.64%	5.64%
Affiliated Entity [Member] \| Related Party Loan Two [Member]
Related Party Transaction [Line Items]
Debt Instrument, Maturity Date		Dec. 16, 2021
Debt Instrument, Face Amount	105,000,000	105,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.86%	5.86%
Affiliated Entity [Member] \| Related Party Loan Three [Member]
Related Party Transaction [Line Items]
Debt Instrument, Maturity Date		Jun. 30, 2019
Debt Instrument, Face Amount	500,000,000	500,000,000
Debt Instrument, Interest Rate, Stated Percentage	3.54%	3.54%
Affiliated Entity [Member] \| Related Party Loan Four [Member]
Related Party Transaction [Line Items]
Debt Instrument, Maturity Date		Oct. 01, 2019
Debt Instrument, Face Amount	250,000,000	250,000,000
Debt Instrument, Interest Rate, Stated Percentage	3.57%	3.57%
Affiliated Entity [Member] \| Related Party Loan Five [Member]
Related Party Transaction [Line Items]
Debt Instrument, Maturity Date		Sep. 30, 2016
Debt Instrument, Face Amount	250,000,000	250,000,000
Debt Instrument, Interest Rate, Stated Percentage	7.44%	7.44%
Affiliated Entity [Member] \| Related Party Loan Six [Member]
Related Party Transaction [Line Items]
Debt Instrument, Maturity Date		Jul. 15, 2021
Debt Instrument, Face Amount	150,000,000	150,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.64%	5.64%
Affiliated Entity [Member] \| Related Party Loan Seven [Member]
Related Party Transaction [Line Items]
Debt Instrument, Maturity Date		Dec. 16, 2021
Debt Instrument, Face Amount	375,000,000	375,000,000
Debt Instrument, Interest Rate, Stated Percentage	5.86%	5.86%
Affiliated Entity [Member] \| Other Investments [Member]
Related Party Transaction [Line Items]
Carrying value of related party loans	2,000,000,000	2,000,000,000	1,500,000,000
Related party net investment income		92,000,000	90,000,000	93,000,000
American Life Insurance Company [Member] \| Other Investments [Member] \| Surplus Notes, Affiliated [Member]
Related Party Transaction [Line Items]
Carrying value of related party loans	100,000,000	100,000,000
Debt Instrument, Frequency of Periodic Payment		semiannually
Debt Instrument, Maturity Date		Jun. 30, 2020
Debt Instrument, Interest Rate, Stated Percentage	3.17%	3.17%
Debt Securities [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Due from (to) Related Party				1,500,000,000
Parent Company [Member] \| Affiliated Entity [Member]
Related Party Transaction [Line Items]
Assets Transferred To Affiliates, Estimated Fair Value			751,000,000
Assets Transferred From Affiliates, Estimated Fair Value			$ 739,000,000