Derivative Financial Instruments (Details 13) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Policyholder benefits and claims	$ 9,119	$ 6,930	$ 17,350	$ 14,394
Changes in estimated fair value related to embedded derivatives
Net derivatives gains (losses)	(394)	(2,199)	549	(1,677)
Changes in estimated fair value of embedded derivatives [Member]
Policyholder benefits and claims	$ 10	$ 67	$ (8)	$ 46

Changes in estimated fair value related to embedded derivatives Abstract.

Name:	met_ChangesInEstimatedFairValueRelatedToEmbeddedDerivativesAbstract
Namespace Prefix:	met
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Net increase (decrease) in the fair value of the embedded derivative or group of embedded derivatives included in earnings in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44A, 44B

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 12-16, 44A, 44B

+ Details

Name:	us-gaap_EmbeddedDerivativeGainLossOnEmbeddedDerivativeNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Provision for benefits, claims and claims settlement expenses incurred during the period net of the effects of contracts assumed and ceded.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 5
-Article 7

+ Details

Name:	us-gaap_PolicyholderBenefitsAndClaimsIncurredNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration