Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 480.5	$ 505.4	$ 288.9
Other Comprehensive Income
Foreign currency translation adjustments	(256.8)	(194.3)	(116.9)
Less: reclassification adjustments recognized in net income	23.3	(0.9)	0.0
Income tax effect	0.0	0.0	(0.6)
Foreign currency translation, net of tax	(233.5)	(195.2)	(117.5)
Available-for-sale securities:
Changes in fair value of available-for-sale securities	0.5	0.7	0.8
Less: recognition of previously unrealized (gains) losses included in net income	0.0	0.0	(1.4)
Income tax effect	0.0	(0.3)	0.2
Available-for-sale securities, net of tax	0.5	0.4	(0.4)
Derivatives instruments:
Changes in fair value of derivative instruments	0.0	(0.6)	0.0
Less: recognition of previously unrealized losses included in net income	2.0	1.9	1.7
Income tax effect	(0.7)	(0.5)	(0.7)
Derivative instruments, net of tax	1.3	0.8	1.0
Defined benefit pension and other postretirement plans:
Net actuarial gains (losses) for the period	14.2	(55.5)	(20.6)
Less: amortization of unrecognized losses, transition obligation and prior service cost included in net income	10.6	10.0	10.8
Less: settlement and curtailment (gains) losses included in net income	(0.2)	0.5	(0.1)
Other	0.4	0.5	1.0
Income tax effect	(6.4)	10.4	(1.3)
Defined benefit pension and other postretirement plans, net of tax	18.6	(34.1)	(10.2)
Other comprehensive loss, net of tax	(213.1)	(228.1)	(127.1)
Total comprehensive income	267.4	277.3	161.8
Less: comprehensive income attributable to noncontrolling interest	21.7	25.7	17.1
Comprehensive Income Attributable to IPG	$ 245.7	$ 251.6	$ 144.7