Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Net income available to IPG common stockholders	$ 251.8	$ 239.9	$ 640.8	$ 594.9
Weighted-average number of common shares outstanding, Basic	390.6	393.5	392.7	392.8
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	3.5	6.3	3.5	5.5
Weighted-average number of common shares outstanding, Diluted	394.1	399.8	396.2	398.3
Earnings per share, Basic	$ 0.64	$ 0.61	$ 1.63	$ 1.51
Earnings per share, Diluted	$ 0.64	$ 0.60	$ 1.62	$ 1.49