Investments (Mortgage Loans by Portfolio Segment) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Company-held mortgage loans held-for-investment, net
Commercial mortgage loans	$ 32,482	$ 33,072
Percentage of loans receivable on commercial mortgage loans	66.20%	71.90%
Agricultural mortgage loans	11,033	11,025
Percentage of loans receivable on agricultural mortgage loans	22.50%	24.00%
Residential mortgage loans	5,494	1,858
Percentage of loans receivable on residential mortgage loans	11.20%	4.00%
Subtotal	49,009mlic_MortgageLoansHeldForInvestment	45,955mlic_MortgageLoansHeldForInvestment
Percentage of loans receivable on subtotal	99.90%	99.90%
Valuation allowances	(258)	(272)	(304)	(393)
Percentage of loans receivable on valuation allowances	(0.50%)	(0.60%)
Subtotal mortgage loans held-for-investment, net	48,751	45,683
Percentage of loans receivable on subtotal mortgage loans held-for-investment, net	99.40%	99.30%
Residential — FVO	308	338
Percentage of residential mortgage loans - FVO	0.60%	0.70%
Mortgage Loans on Real Estate, Commercial and Consumer, Net	49,059	46,021
Percentage of loans receivable on mortgage loans, at estimated fair value	100.00%	100.00%
Mortgage loans held-for-sale	0us-gaap_LoansReceivableHeldForSaleNet	3us-gaap_LoansReceivableHeldForSaleNet
Percentage of mortgage loans held-for-sale	0.00%	0.00%
Total mortgage loans, net	$ 49,059us-gaap_MortgageLoansOnRealEstate	$ 46,024us-gaap_MortgageLoansOnRealEstate
Percentage of loans held for sale on total mortgage loans, net	100.00%	100.00%

The balance represents the amount of loans that are secured by real estate mortgages.

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- Definition

Percentage of Allowance For Loan And Lease Losses on Real Estate to total Mortgage Loans on Real Estate.

+ References

No definition available.

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- Definition

Percentage of Consumer Mortgage Loans and Leases Receivable to total Mortgage Loans on Real Estate.

+ References

No definition available.

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- Definition

Percentage of loans and leases receivable consumer other to total mortgage loans on real estate.

+ References

No definition available.

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- Definition

Percentage of Commercial Agricultural Loans Receivable to total Mortgage Loans on Real Estate.

+ References

No definition available.

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Percentage of Commercial Mortgage Loans Receivable to total Mortgage Loans on Real Estate.

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No definition available.

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- Definition

Percentage of Loans Receivable Held For Sale, Net to total Mortgage Loans on Real Estate.

+ References

No definition available.

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- Definition

Percentage of Mortgage Loans Held-for-investment, net to total Mortgage Loans on Real Estate.

+ References

No definition available.

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- Definition

Percentage of Mortgage Loans Held For Investment to total Mortgage Loans on Real Estate.

+ References

No definition available.

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- Definition

Percentage of Commercial Agricultural Loans Receivable to total Mortgage Loans on Real Estate.

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No definition available.

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- Definition

Percentage of Mortgage Loans On Real Estate to total Mortgage Loans on Real Estate.

+ References

No definition available.

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- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 310

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- Definition

Amount before allowance of consumer mortgage. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes subordinated loans such as home equity lines of credit and loans and leases covered under loss sharing agreements.

+ References

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- Definition

Amount before allowance of consumer loans and leases not otherwise specified in the taxonomy. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

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- Definition

Amount before allowance of loans issued to agricultural institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

+ References

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

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Amount before allowance of mortgage loans on existing land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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Amount classified as loans attributable to disposal group held for sale or disposed of. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

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Total carrying amount of mortgage loans as of the balance sheet date.

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The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

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