Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net (Loss) Income Attributable to Graphic Packaging Holding Company	$ (12.7)	$ 57.9
Weighted Average Shares:
Basic (shares)	288,900,000	297,500,000
Dilutive effect of RSUs (shares)	0	700,000
Diluted (shares)	288,900,000	298,200,000
Earnings Per Share - Basic (in dollars per share)	$ (0.04)	$ 0.19
Earnings Per Share - Diluted (in dollars per share)	$ (0.04)	$ 0.19
Potentially dilutive restricted stock units	1,085,683