Revenue, Percent

No definition available.

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- Definition

Revenue from Contract with Customer, Percent

+ References

No definition available.

+ Details

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- Definition

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (b)
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+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 40
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Balance Type:	debit
Period Type:	instant

- Definition

Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from change in measure of progress which increases (decreases) right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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Balance Type:	credit
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- Definition

Amount of decrease in right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time from transfer to receivable due to right to consideration becoming unconditional.

+ References

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-Publisher FASB
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Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

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-Publisher FASB
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+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue recognized from performance obligation satisfied or partially satisfied in previous reporting periods. Includes, but is not limited to, change in transaction price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Topic 606
-SubTopic 10
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- Definition

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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- 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

No definition available.

+ Details

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- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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Revenue - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Revenue - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings	$ 14,347		$ 13,504	$ 13,140
Percentage of total revenue	1.00%
Cumulative catch-up adjustment to revenue, change in measure of progress	$ 331
Contract with customer, asset, reclassified to receivable	347
Contract with customer, liability, revenue recognized	582
Contract with customer, performance obligation satisfied in previous period	51
Capitalized contract cost, amortization	$ 998
Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings		$ 364	$ 364
Health Brokerage and Consulting
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer, percent	70.00%
Marsh Insurance Group
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, remaining performance obligation	$ 32
Mercer Consulting Group
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, remaining performance obligation	486
Oliver Wyman Group Consulting Group
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue, remaining performance obligation	2
Deferred Implementation Costs
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized contract cost, net	41
Costs to Obtain
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized contract cost, net	206
Costs to Fulfill
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Capitalized contract cost, net	$ 227