Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Net income available to IPG common stockholders	$ 229.6	$ 263.3	$ 389.0	$ 355.0
Weighted-average number of common shares outstanding, Basic	393.1	393.3	393.8	392.4
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	3.7	5.7	3.7	5.2
Weighted-average number of common shares outstanding, Diluted	396.8	399.0	397.5	397.6
Earnings per share, Basic	$ 0.58	$ 0.67	$ 0.99	$ 0.90
Earnings per share, Diluted	$ 0.58	$ 0.66	$ 0.98	$ 0.89