XML 121 R108.htm IDEA: XBRL DOCUMENT
v3.24.3

Fair Value (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | $ 293,779 | $ 281,412
Equity securities | 746 | 757
Unit-linked and FVO securities | 9,289 | 10,331
Short-term investments | 4,609 | 6,045
Derivative assets | 8,172 | 8,737
Market risk benefits, at estimated fair value | 310 | 286
Separate account assets | 148,809 | 144,634
Liabilities [Abstract] |  |
Derivative liabilities | 6,357 | 6,298
Embedded derivatives within liability host contracts | 119 | 93
Market risk benefits, at estimated fair value | 3,117 | 3,179
Separate account liabilities | 148,809 | 144,634
Recurring |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 293,779 | 281,412
Equity securities | 746 | 757
Unit-linked and FVO securities | 9,289 | 10,331
Short-term investments | 4,337 | 5,797
Other investments | 3,155 | 1,386
Derivative assets | 8,172 | 8,737
Market risk benefits, at estimated fair value | 310 | 286
Reinsured MRB Assets | 16 | 18
Separate account assets | 148,809 | 144,634
Total assets | 468,613 | 453,358
Investments, fair value | 51 | 52
Liabilities [Abstract] |  |
Derivative liabilities | 6,357 | 6,298
Embedded derivatives within liability host contracts | 119 | 93
Market risk benefits, at estimated fair value | 3,117 | 3,179
Total liabilities | 9,598 | 9,578
Recurring | Interest rate |  |
Assets [Abstract] |  |
Derivative assets | 3,426 | 3,675
Liabilities [Abstract] |  |
Derivative liabilities | 2,996 | 2,984
Recurring | Foreign currency exchange rate contracts |  |
Assets [Abstract] |  |
Derivative assets | 4,186 | 4,418
Liabilities [Abstract] |  |
Derivative liabilities | 2,923 | 2,744
Recurring | Credit |  |
Assets [Abstract] |  |
Derivative assets | 271 | 236
Liabilities [Abstract] |  |
Derivative liabilities | 76 | 84
Recurring | Equity market contracts |  |
Assets [Abstract] |  |
Derivative assets | 289 | 408
Liabilities [Abstract] |  |
Derivative liabilities | 362 | 486
Recurring | Separate account liabilities |  |
Liabilities [Abstract] |  |
Separate account liabilities | 5 | 8
Recurring | U.S. corporate |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 84,851 | 80,717
Recurring | Foreign corporate |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 56,752 | 55,444
Recurring | Foreign government |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 44,132 | 45,489
Recurring | U.S. government and agency |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 34,676 | 32,252
Recurring | RMBS |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 35,264 | 29,096
Recurring | ABS & CLO |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 17,520 | 17,294
Recurring | Municipals |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 10,798 | 11,171
Recurring | CMBS |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 9,786 | 9,949
Recurring | Level 1 |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 16,650 | 15,330
Equity securities | 430 | 429
Unit-linked and FVO securities | 7,846 | 7,520
Short-term investments | 3,155 | 5,103
Other investments | 44 | 48
Derivative assets | 17 | 11
Market risk benefits, at estimated fair value | 0 | 0
Reinsured MRB Assets | 0 | 0
Separate account assets | 69,799 | 66,229
Total assets | 97,941 | 94,670
Liabilities [Abstract] |  |
Derivative liabilities | 8 | 16
Embedded derivatives within liability host contracts | 0 | 0
Market risk benefits, at estimated fair value | 0 | 0
Total liabilities | 8 | 20
Recurring | Level 1 | Interest rate |  |
Assets [Abstract] |  |
Derivative assets | 2 | 1
Liabilities [Abstract] |  |
Derivative liabilities | 2 | 5
Recurring | Level 1 | Foreign currency exchange rate contracts |  |
Assets [Abstract] |  |
Derivative assets | 2 | 2
Liabilities [Abstract] |  |
Derivative liabilities | 0 | 0
Recurring | Level 1 | Credit |  |
Assets [Abstract] |  |
Derivative assets | 0 | 0
Liabilities [Abstract] |  |
Derivative liabilities | 0 | 0
Recurring | Level 1 | Equity market contracts |  |
Assets [Abstract] |  |
Derivative assets | 13 | 8
Liabilities [Abstract] |  |
Derivative liabilities | 6 | 11
Recurring | Level 1 | Separate account liabilities |  |
Liabilities [Abstract] |  |
Separate account liabilities | 0 | 4
Recurring | Level 1 | U.S. corporate |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 0
Recurring | Level 1 | Foreign corporate |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 0
Recurring | Level 1 | Foreign government |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 0
Recurring | Level 1 | U.S. government and agency |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 16,650 | 15,327
Recurring | Level 1 | RMBS |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 3
Recurring | Level 1 | ABS & CLO |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 0
Recurring | Level 1 | Municipals |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 0
Recurring | Level 1 | CMBS |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 0
Recurring | Level 2 |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 241,373 | 233,135
Equity securities | 74 | 79
Unit-linked and FVO securities | 267 | 1,708
Short-term investments | 1,176 | 667
Other investments | 2,016 | 363
Derivative assets | 8,126 | 8,688
Market risk benefits, at estimated fair value | 0 | 0
Reinsured MRB Assets | 0 | 0
Separate account assets | 77,991 | 77,258
Total assets | 331,023 | 321,898
Liabilities [Abstract] |  |
Derivative liabilities | 6,344 | 6,101
Embedded derivatives within liability host contracts | 0 | 0
Market risk benefits, at estimated fair value | 0 | 0
Total liabilities | 6,349 | 6,105
Recurring | Level 2 | Interest rate |  |
Assets [Abstract] |  |
Derivative assets | 3,424 | 3,674
Liabilities [Abstract] |  |
Derivative liabilities | 2,994 | 2,805
Recurring | Level 2 | Foreign currency exchange rate contracts |  |
Assets [Abstract] |  |
Derivative assets | 4,159 | 4,393
Liabilities [Abstract] |  |
Derivative liabilities | 2,918 | 2,737
Recurring | Level 2 | Credit |  |
Assets [Abstract] |  |
Derivative assets | 271 | 228
Liabilities [Abstract] |  |
Derivative liabilities | 76 | 84
Recurring | Level 2 | Equity market contracts |  |
Assets [Abstract] |  |
Derivative assets | 272 | 393
Liabilities [Abstract] |  |
Derivative liabilities | 356 | 475
Recurring | Level 2 | Separate account liabilities |  |
Liabilities [Abstract] |  |
Separate account liabilities | 5 | 4
Recurring | Level 2 | U.S. corporate |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 70,349 | 67,003
Recurring | Level 2 | Foreign corporate |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 41,047 | 40,813
Recurring | Level 2 | Foreign government |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 44,091 | 45,438
Recurring | Level 2 | U.S. government and agency |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 18,026 | 16,925
Recurring | Level 2 | RMBS |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 33,367 | 27,495
Recurring | Level 2 | ABS & CLO |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 15,138 | 15,191
Recurring | Level 2 | Municipals |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 10,798 | 11,171
Recurring | Level 2 | CMBS |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 8,557 | 9,099
Recurring | Level 3 |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 35,756 | 32,947
Equity securities | 242 | 249
Unit-linked and FVO securities | 1,176 | 1,103
Short-term investments | 6 | 27
Other investments | 1,095 | 975
Derivative assets | 29 | 38
Market risk benefits, at estimated fair value | 310 | 286
Reinsured MRB Assets | 16 | 18
Separate account assets | 1,019 | 1,147
Total assets | 39,649 | 36,790
Liabilities [Abstract] |  |
Derivative liabilities | 5 | 181
Embedded derivatives within liability host contracts | 119 | 93
Market risk benefits, at estimated fair value | 3,117 | 3,179
Total liabilities | 3,241 | 3,453
Recurring | Level 3 | Interest rate |  |
Assets [Abstract] |  |
Derivative assets | 0 | 0
Liabilities [Abstract] |  |
Derivative liabilities | 0 | 174
Recurring | Level 3 | Foreign currency exchange rate contracts |  |
Assets [Abstract] |  |
Derivative assets | 25 | 23
Liabilities [Abstract] |  |
Derivative liabilities | 5 | 7
Recurring | Level 3 | Credit |  |
Assets [Abstract] |  |
Derivative assets | 0 | 8
Liabilities [Abstract] |  |
Derivative liabilities | 0 | 0
Recurring | Level 3 | Equity market contracts |  |
Assets [Abstract] |  |
Derivative assets | 4 | 7
Liabilities [Abstract] |  |
Derivative liabilities | 0 | 0
Recurring | Level 3 | Separate account liabilities |  |
Liabilities [Abstract] |  |
Separate account liabilities | 0 | 0
Recurring | Level 3 | U.S. corporate |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 14,502 | 13,714
Recurring | Level 3 | Foreign corporate |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 15,705 | 14,631
Recurring | Level 3 | Foreign government |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 41 | 51
Recurring | Level 3 | U.S. government and agency |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 0
Recurring | Level 3 | RMBS |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 1,897 | 1,598
Recurring | Level 3 | ABS & CLO |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 2,382 | 2,103
Recurring | Level 3 | Municipals |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | 0 | 0
Recurring | Level 3 | CMBS |  |
Assets [Abstract] |  |
Estimated Fair Value of Fixed Maturity Securities AFS | $ 1,229 | $ 850

X
- Definition Investments for which the FVO has been elected, or are otherwise required to be carried at estimated fair value. + References No definition available. + Details
Name: | met_ContractholderDirectedEquitySecuritiesAndFairValueOptionSecuritiesAtEstimatedFairValue
Namespace Prefix: | met_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investments in fund assets. + References No definition available. + Details
Name: | met_InvestmentFunds
Namespace Prefix: | met_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Reinsured MRB Assets + References No definition available. + Details
Name: | met_ReinsuredMRBAssets
Namespace Prefix: | met_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of asset recognized for present right to economic benefit. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 100 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-100 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AssetsFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 103 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-103 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 100 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-100 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481830/320-10-45-1 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4B -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 22 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483444/210-20-55-22 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483466/210-20-50-3 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483444/210-20-55-7 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (c)(2) -SubTopic 20 -Topic 860 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481326/860-20-50-4D + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4B -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 22 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483444/210-20-55-22 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483466/210-20-50-3 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147483444/210-20-55-7 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (c)(2) -SubTopic 20 -Topic 860 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481326/860-20-50-4D + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as a liability. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4B -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4B + Details
Name: | us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 100 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-100 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-14 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 9 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-9 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482736/825-10-45-1A Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2E -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LiabilitiesFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of asset position for contract or contract feature in long-duration contract issued by insurance entity that both protects contract holder from other-than-nominal capital market risk and exposes insurance entity to other-than-nominal capital market risk. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 7B -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-7B Reference 5: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 29G -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-29G + Details
Name: | us-gaap_MarketRiskBenefitAssetAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of liability position for contract or contract feature in long-duration contract issued by insurance entity that both protects contract holder from other-than-nominal capital market risk and exposes insurance entity to other-than-nominal capital market risk. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 7B -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-7B Reference 5: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 29G -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-29G + Details
Name: | us-gaap_MarketRiskBenefitLiabilityAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of asset at fair value held for benefit of separate account policyholder. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-17 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-14 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 9 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-9 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480109/944-80-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480141/944-80-45-1 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(11)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480141/944-80-45-2 + Details
Name: | us-gaap_SeparateAccountAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of liability for variable contract in which all or portion of contract holder's funds is allocated to specific separate account and supported by assets held in separate account. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 9 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-9 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480141/944-80-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480109/944-80-50-2 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 18 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480078/944-80-55-18 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480109/944-80-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 80 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480141/944-80-45-2 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(18)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 + Details
Name: | us-gaap_SeparateAccountsLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(5)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(8)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_ShortTermInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CreditRiskContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_EquityContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=met_DerivativeLiabilitiesWithinSeparateAccountsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_DomesticCorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_ForeignCorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |