Incentive Compensation Plans Stock-based Compensation Awards (Details) - 6 months ended Jun. 30, 2015 - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Total
Share-based Compensation Award [Abstract]
Incentive Compensation Plan Initiation Year	2014
Incentive Compensation Plans
Granted awards	3.5
Stock settled awards
Incentive Compensation Plans
Granted awards	0.7
Weighted Average Grant Date Fair Value	$ 22.12
Performance based awards
Incentive Compensation Plans
Granted awards	2.8
Weighted Average Grant Date Fair Value	$ 20.88
Cash awards
Incentive Compensation Plans
Performance Cash awards granted during the period target value	$ 32.8
Restricted Cash awards granted during the period target value	$ 0.7
Cash awards vesting period	3 years

Target value of all cash awards granted during the period (settled in shares or cash)

No definition available.

Name:	ipg_CashAwardsGrantedDuringPeriodTargetValue
Namespace Prefix:	ipg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Incentive Compensation Plan Initiation Year

+ References

No definition available.

+ Details

Name:	ipg_IncentiveCompensationPlanInitiationYear
Namespace Prefix:	ipg_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Restricted Cash Plan - cash awards granted during the period target value

+ References

No definition available.

+ Details

Name:	ipg_RestrictedCashPlancashawardsgrantedduringtheperiodtargetvalue
Namespace Prefix:	ipg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Share-based Compensation Award [Abstract]

+ References

No definition available.

+ Details

Name:	ipg_SharebasedCompensationAwardAbstract
Namespace Prefix:	ipg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- 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

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=ipg_StockSettledAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=ipg_PerformanceBasedAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=ipg_CashawardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: