Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net Income Attributable to Graphic Packaging Holding Company	$ 52.1	$ 63.8	$ 39.4	$ 121.7
Weighted Average Shares:
Basic (shares)	279.9	295.2	284.4	296.3
Dilutive effect of RSUs (shares)	0.6	0.5	0.8	0.7
Diluted (shares)	280.5	295.7	285.2	297.0
Earnings Per Share - Basic (in dollars per share)	$ 0.19	$ 0.22	$ 0.14	$ 0.41
Earnings Per Share - Diluted (in dollars per share)	$ 0.19	$ 0.22	$ 0.14	$ 0.41