Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Statement of Other Comprehensive Income [Abstract]
NET INCOME	$ 86.1	$ 105.5	$ 27.6	$ 59.8
OTHER COMPREHENSIVE INCOME (LOSS)
Foreign currency translation adjustments	(74.5)	(66.3)	(113.3)	(21.2)
Available-for-sale securities:
Changes in market value of available-for sale securities	0.4	135.0	0.8	135.5
Less: recognition of previously unrealized (gains) losses included in net income	(0.4)	0	(1.4)	0.6
Available-for-sale securities, Income tax effect	0.1	(50.6)	0.2	(50.6)
Available-for-sale securities, net of tax	0.1	84.4	(0.4)	85.5
Derivative instruments:
Changes in fair value of derivative instruments	0	(15.8)	0	(18.6)
Less: recognition of previously unrealized losses in net income	0.5	0	0.9	0
Derivative instruments, Income tax effect	(0.2)	7.7	(0.4)	7.7
Derivative instruments, net of tax	0.3	(8.1)	0.5	(10.9)
Defined benefit pension and other postretirement plans:
Net actuarial gains for the period	1.1	1.3	0	1.0
Less: amortization of unrecognized losses, transition obligation and prior service cost included in net income	2.7	1.8	5.5	3.7
Other	(0.2)	0	(0.7)	(0.1)
Defined benefit pension and other postretirement plans, Income tax effect	(1.3)	(1.2)	(2.0)	(1.7)
Defined benefit pension and other postretirement plans, Net of tax	2.3	1.9	2.8	2.9
Other comprehensive (loss) income, net of tax	(71.8)	11.9	(110.4)	56.3
Total Comprehensive Income (Loss)	14.3	117.4	(82.8)	116.1
Less: comprehensive income (loss) attributable to noncontrolling interests	1.5	2.0	(1.9)	(0.2)
Comprehensive Income (Loss) Attributable to IPG	$ 12.8	$ 115.4	$ (80.9)	$ 116.3