Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net income available to IPG common stockholders	$ 4.7	$ (8.0)
Weighted-average number of common shares outstanding, Basic	387.7	384.5
Dilutive effect of stock options and restricted shares	4.0
Weighted-average number of common shares outstanding, Diluted	391.7	384.5
Loss per share, Basic	$ 0.01	$ (0.02)
Loss per share, Diluted	$ 0.01	$ (0.02)