Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Net income available to IPG common stockholders	$ 110.4	$ 126.0
Weighted-average number of common shares outstanding, Basic	378.4	385.8
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	2.2	1.6
Weighted-average number of common shares outstanding, Diluted	380.6	387.4
Earnings per share, Basic	$ 0.29	$ 0.33
Earnings per share, Diluted	$ 0.29	$ 0.33