XML 73 R55.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Supplemental Disclosures (Schedule of Analysis for Doubtful Accounts) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward] |  |  |
Balance at beginning of year | $ 110 | $ 96 | $ 87
Provision charged to operations | 34 | 31 | 31
Accounts written-off, net of recoveries | (24) | (17) | (20)
Effect of exchange rate changes and other | (8) | 0 | (2)
Balance at end of year | $ 112 | $ 110 | $ 96

X
- Definition Allowance For Doubtful Accounts Receivable, Effect Of Exchange Rate Changes And Other + References No definition available. + Details
Name: | mmc_AllowanceForDoubtfulAccountsReceivableEffectOfExchangeRateChangesAndOther
Namespace Prefix: | mmc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Allowance For Doubtful Accounts Receivable, Write-offs, Net Of Recoveries + References No definition available. + Details
Name: | mmc_AllowanceForDoubtfulAccountsReceivableWriteoffsNetOfRecoveries
Namespace Prefix: | mmc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of expense related to write-down of receivables to the amount expected to be collected. Includes, but is not limited to, accounts receivable and notes receivable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.5) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130534-203044 + Details
Name: | us-gaap_ProvisionForDoubtfulAccounts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration