Consolidated Statements of Comprehensive Income (Loss) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 92.8		$ 49.2		$ 174.1		$ 76.8
OTHER COMPREHENSIVE (LOSS) INCOME
Foreign currency translation adjustments	(113.5)		24.0		(89.0)		(89.3)
Less: reclassification adjustments recognized in net income	0		0		(0.9)		0
Foreign Currency Transaction and Translation Adjustment, Net of Tax	(113.5)		24.0		(89.9)		(89.3)
Available-for-sale securities:
Changes in market value of available-for sale securities	0.2		(0.1)		0.4		0.7
Less: recognition of previously unrealized gains included in net income	0		0		0		(1.4)
Income tax effect	(0.3)		0		(0.3)		0.2
Available-for-sale securities, net of tax	(0.1)		(0.1)		0.1		(0.5)
Derivative instruments:
Changes in fair value of derivative instruments	0		0		(0.6)		0
Less: recognition of previously unrealized losses included in net income	0.5		0.4		1.4		1.3
Income tax effect	(0.2)		(0.1)		(0.3)		(0.5)
Derivative instruments, net of tax	0.3		0.3		0.5		0.8
Defined benefit pension and other postretirement plans:
Net actuarial losses for the period	0		0		(0.3)		0
Less: amortization of unrecognized losses, transition obligation and prior service cost included in net income	2.6	[1]	2.7	[1]	7.6	[1]	8.2	[1]
Other	(0.1)		(0.2)		(0.3)		(0.9)
Income tax effect	(1.0)		(0.8)		(2.3)		(2.8)
Defined benefit pension and other postretirement plans, net of tax	1.5		1.7		4.7		4.5
Other comprehensive (loss) income, net of tax	(111.8)		25.9		(84.6)		(84.5)
TOTAL COMPREHENSIVE (LOSS) INCOME	(19.0)		75.1		89.5		(7.7)
Less: comprehensive income (loss) attributable to noncontrolling interests	3.4		0.7		5.3		(1.2)
COMPREHENSIVE (LOSS) INCOME ATTRIBUTABLE TO IPG	$ (22.4)		$ 74.4		$ 84.2		$ (6.5)

[1] These accumulated other comprehensive loss components are included in the computation of net periodic cost. See Note 10 for further information.