XML 62 R51.htm IDEA: XBRL DOCUMENT
v3.25.2

Financial Instruments - Effect of Net Investment Hedges (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Foreign exchange contracts |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Amount of Pretax Loss (Gain) Recognized in Other Comprehensive Income | $ 38 | $ 5 | $ 65 | $ 3
Foreign exchange contracts | Other (income) expense, net |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Amount of Pretax Gain Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing | 5 | 1 | 8 | 1
Euro-denominated notes |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Amount of Pretax Loss (Gain) Recognized in Other Comprehensive Income | 411 | (34) | 541 | (96)
Euro-denominated notes | Other (income) expense, net |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Amount of Pretax Gain Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing | $ 0 | $ 0 | $ 0 | $ 0

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 182 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480401/815-10-55-182 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(5) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(4) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(6) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CCC -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CCC Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CCC -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CCC Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CCC -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CCC Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CC -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CC Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 17: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 18: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 19: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 20: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4C -Subparagraph (bb) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4C Reference 21: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4D -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4D Reference 22: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4E + Details
Name: | us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before tax and reclassification, of gain (loss) from derivative designated and qualifying as net investment hedge. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 182 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480401/815-10-55-182 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CCC -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CCC + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, before tax, of reclassification from accumulated other comprehensive income (AOCI) for gain (loss) from derivative designated and qualifying as net investment hedge. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 182 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480401/815-10-55-182 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4CCC -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4CCC + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossReclassificationBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_OtherNonoperatingIncomeExpenseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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