XML 74 R55.htm IDEA: XBRL DOCUMENT
v3.19.2

Acquisitions and Dispositions (Pro-Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018
Business Combinations [Abstract] |  |  |  |
Revenue | $ 4,346 | $ 4,339 | $ 8,863 | $ 8,902
Net income attributable to the Company | $ 463 | $ 513 | $ 1,134 | $ 626
Basic net income per share: |  |  |  |
Basic net income per share attributable to the Company (in dollars per share) | $ 0.91 | $ 1.01 | $ 2.24 | $ 1.23
Diluted net income per share: |  |  |  |
Diluted net income per share attributable to the Company (in dollars per share) | $ 0.90 | $ 1.00 | $ 2.22 | $ 1.22

X
- Definition Business Acquisition, Pro Forma Earnings Per Share, Basic [Abstract] + References No definition available. + Details
Name: | mmc_BusinessAcquisitionProFormaEarningsPerShareBasicAbstract
Namespace Prefix: | mmc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Business Acquisition, Pro Forma Earnings Per Share, Diluted [Abstract] + References No definition available. + Details
Name: | mmc_BusinessAcquisitionProFormaEarningsPerShareDilutedAbstract
Namespace Prefix: | mmc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per basic share amount of pro forma income from continuing operations, after tax, as if the business combination had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per diluted share amount of pro forma income from continuing operations, after tax, as if the business combination had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(3) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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