Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net Income Attributable to Graphic Packaging Holding Company	$ 63.7	$ 52.1	$ 103.1	$ 173.8
Weighted Average Shares:
Basic (shares)	277.0	292.9	281.9	295.2
Dilutive effect of RSUs (shares)	0.7	0.8	0.8	0.7
Diluted (shares)	277.7	293.7	282.7	295.9
Earnings Per Share - Basic (in dollars per share)	$ 0.23	$ 0.18	$ 0.37	$ 0.59
Earnings Per Share - Diluted (in dollars per share)	$ 0.23	$ 0.18	$ 0.36	$ 0.59