Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Other Comprehensive Income [Abstract]
Net income	$ 464.6	$ 551.5	$ 281.2
Other Comprehensive (Loss) Income
Foreign currency translation adjustments	9.7	(92.1)	35.9
Available-for-sale securities:
Changes in market value of available-for-sale securities	0.4	(0.1)	0.5
Less: recognition of previously unrealized losses (gains) included in net income	0.7	0.3	(0.2)
Available-for-sale securities, Income tax effect	(0.5)	0	0.1
Available-for-sale securities, Net of tax	0.6	0.2	0.4
Derivatives instruments:
Changes in fair value of derivative instruments	(21.9)	0	0
Less: recognition of previously unrealized losses included in net income	0.3	0	0
Derivative instruments, Income tax effect	8.9	0	0
Derivative instruments, Net of tax	(12.7)	0	0
Defined benefit pension and other postretirement plans:
Net actuarial gains (losses) for the period	(67.9)	(25.7)	18.1
Less: amortization of unrecognized losses, transition obligation and prior service cost included in net income	7.7	7.5	10.8
Less: settlement and curtailment losses included in net income	0.7	0	1.4
Other	(3.4)	2.4	(1.6)
Defined benefit pension and other postretirement plans, Income tax effect	1.9	(1.5)	(5.5)
Defined benefit pension and other postretirement plans, Net of tax	(61.0)	(17.3)	23.2
Other comprehensive (loss) income, Net of tax	(63.4)	(109.2)	59.5
Total comprehensive income	401.2	442.3	340.7
Less: comprehensive income attributable to noncontrolling interest	16.8	16.7	22.0
Comprehensive Income Attributable to IPG	$ 384.4	$ 425.6	$ 318.7