Junior Subordinated Debt Securities (Junior Subordinated Debt Securities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Junior Subordinated Notes	$ 3,193us-gaap_JuniorSubordinatedNotes	$ 3,193us-gaap_JuniorSubordinatedNotes
MetLife Inc $500M Maturing 2069 [Member]
Debt Instrument [Line Items]
Issue Date	Jul. 08, 2009
Face Value	500
Debt Instrument, Interest Rate, Stated Percentage	10.75%
Debt Conversion, Converted Instrument, Expiration or Due Date, Month and Year	2039-08
Debt Instrument, Description of Variable Rate Basis	LIBOR + 7.548%
Debt Instrument, Basis Spread on Variable Rate	7.548%
Final Maturity	Aug. 01, 2069
Debt Instrument, Principal Outstanding	500	500
MetLife Capital Trust X $750M Maturing 2068 [Member]
Debt Instrument [Line Items]
Issue Date	Apr. 08, 2008
Face Value	750
Debt Instrument, Interest Rate, Stated Percentage	9.25%
Debt Conversion, Converted Instrument, Expiration or Due Date, Month and Year	2038-04
Debt Instrument, Description of Variable Rate Basis	LIBOR + 5.540%
Debt Instrument, Basis Spread on Variable Rate	5.54%
Final Maturity	Apr. 08, 2068
Debt Instrument, Principal Outstanding	750	750
MetLife Capital Trust IV $700M Maturing 2067 [Member]
Debt Instrument [Line Items]
Issue Date	Dec. 15, 2007
Face Value	700
Debt Instrument, Interest Rate, Stated Percentage	7.875%
Debt Conversion, Converted Instrument, Expiration or Due Date, Month and Year	2037-12
Debt Instrument, Description of Variable Rate Basis	LIBOR + 3.960%
Debt Instrument, Basis Spread on Variable Rate	3.96%
Final Maturity	Dec. 15, 2067
Debt Instrument, Principal Outstanding	695	695
MetLife Inc $1,250M Maturing 2066 [Member]
Debt Instrument [Line Items]
Issue Date	Dec. 19, 2006
Face Value	1,250
Debt Instrument, Interest Rate, Stated Percentage	6.40%
Debt Conversion, Converted Instrument, Expiration or Due Date, Month and Year	2036-12
Debt Instrument, Description of Variable Rate Basis	LIBOR + 2.205%
Debt Instrument, Basis Spread on Variable Rate	2.205%
Final Maturity	Dec. 15, 2066
Debt Instrument, Principal Outstanding	$ 1,248	$ 1,248

The expiration, mandatory redemption, or due date, month and year (YYYY-MM), of the financial instrument issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

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- 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

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- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

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- Definition

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

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

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- 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

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- Definition

Date the debt instrument was issued, in CCYY-MM-DD format.

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- 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

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

+ References

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

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