Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net income (loss) available to IPG common stockholders	$ 5.4	$ (1.8)
Weighted-average number of common shares outstanding, Basic	400.6
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	8.7
Weighted-average number of common shares outstanding, Diluted	409.3
Weighted Average Number of Shares Outstanding, Basic and Diluted		411.1
Earnings per share, Basic	$ 0.01	$ 0.00
Earnings per share, Diluted	$ 0.01	$ 0.00