Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
REVENUE	$ 7,846.6	$ 7,613.8	$ 7,537.1
OPERATING EXPENSES:
Salaries and related expenses	5,038.1	4,857.7	4,820.4
Office and general expenses	1,870.5	1,884.2	1,928.3
Total operating expenses	6,908.6	6,741.9	6,748.7
OPERATING INCOME	938.0	871.9	788.4
EXPENSES AND OTHER INCOME:
Interest expense	(90.6)	(85.8)	(84.9)
Interest income	20.1	22.8	27.4
Other expense, net	(37.3)	(46.7)	(10.2)
Total (expenses) and other income	(107.8)	(109.7)	(67.7)
Income before income taxes	830.2	762.2	720.7
Provision for income taxes	198.0	282.8	216.5
Income of consolidated companies	632.2	479.4	504.2
Equity in net income of unconsolidated affiliates	0.3	1.1	1.2
NET INCOME	632.5	480.5	505.4
Net income attributable to noncontrolling interests	(24.0)	(25.9)	(28.3)
NET INCOME AVAILABLE TO IPG COMMON STOCKHOLDERS	$ 608.5	$ 454.6	$ 477.1
Earnings per share available to IPG common stockholders:
Basic	$ 1.53	$ 1.11	$ 1.14
Diluted	$ 1.49	$ 1.09	$ 1.12
Weighted-average number of common shares outstanding:
Basic	397.9	408.1	419.2
Diluted	408.0	415.7	425.4
Dividends declared per common share	$ 0.60	$ 0.48	$ 0.38