Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Statement [Abstract]
REVENUE	$ 1,543.0	$ 1,506.8
OPERATING EXPENSES:
Salaries and related expenses	1,132.1	1,104.9
Office and general expenses	453.3	441.3
Total operating expenses	1,585.4	1,546.2
OPERATING LOSS	(42.4)	(39.4)
EXPENSES AND OTHER INCOME:
Interest expense	(36.8)	(32.6)
Interest income	6.4	8.0
Other income (expense), net	1.8	(1.3)
Total (expenses) and other income	(28.6)	(25.9)
Loss before income taxes	(71.0)	(65.3)
Benefit of income taxes	(12.4)	(19.2)
Loss of consolidated companies	(58.6)	(46.1)
Equity in net income of unconsolidated affiliates	0.1	0.4
NET LOSS	(58.5)	(45.7)
Net loss attributable to noncontrolling interests	2.2	2.7
NET LOSS ATTRIBUTABLE TO IPG	(56.3)	(43.0)
Dividends on preferred stock	(2.9)	(2.9)
NET LOSS AVAILABLE TO IPG COMMON STOCKHOLDERS	$ (59.2)	$ (45.9)
Loss per share available to IPG common stockholders - basic and diluted	$ (0.14)	$ (0.10)
Weighted-average number of common shares outstanding - basic and diluted	414.2	437.6
Dividends declared per common share	$ 0.075	$ 0.060