Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Earnings Per Share [Abstract]
Net income available to IPG common stockholders	$ (85.4)	$ 110.4
Weighted-average number of common shares outstanding, Basic	372.5	378.4
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	2.5	2.2
Weighted-average number of common shares outstanding, Diluted	375.0	380.6
Earnings per share, Basic	$ (0.23)	$ 0.29
Earnings per share, Diluted	$ (0.23)	$ 0.29