Investments (Investment in Leverage Leases) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Investment in leveraged leases
Rental receivables, net	$ 1,491	$ 1,564
Estimated residual values	1,325	1,474
Subtotal	2,816	3,038
Unearned income	(870)	(1,040)
Investment in leveraged leases	$ 1,946	$ 1,998

This element represents the subtotal of rental receivables, net plus estimated residual value of the leased assets.

No definition available.

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Namespace Prefix:	met_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The estimated portion of pretax income and investment tax credit remaining to be allocated to income over the lease term.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 30

-Paragraph 14

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7662307&loc=d3e42840-112730

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The net investment in arrangements meeting the criteria for classification as leveraged leases including deferred taxes.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 35

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=7662473&loc=d3e43930-112732

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 30

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=7662307&loc=d3e42840-112730

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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- Definition

This element represents leveraged lease rentals receivable, net of that portion of the rental applicable to principal and interest on the nonrecourse debt.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 30

-Paragraph 14

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7662307&loc=d3e42840-112730

+ Details

Name:	us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureRentalReceivablesNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The estimate of the value of the leased asset at the end of the lease term.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 30

-Paragraph 14

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7662307&loc=d3e42840-112730

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant