Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
3 Months Ended | |
|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
|
| Earnings Per Share [Abstract] | ||
| Net income available to IPG common stockholders | $ 21.5 | $ 5.4 |
| Weighted-average number of common shares outstanding, Basic | 391.7 | 400.6 |
| Restricted stock, stock options and other equity awards | 7.6 | 8.7 |
| Weighted-average number of common shares outstanding, Diluted | 399.3 | 409.3 |
| Earnings per share, Basic | $ 0.05 | $ 0.01 |
| Earnings per share, Diluted | $ 0.05 | $ 0.01 |