Background - Narrative (Details)	12 Months Ended
	Dec. 31, 2017 segment $ / shares	Dec. 31, 2016 $ / shares	May 15, 2016 $ / shares
Business Combination, Consideration Transferred
Number of reportable segments | segment	2
Common stock, par value (usd per share)	$ 0.01	$ 0.01	$ 0.01
WestRock, Rock-Tenn and MWV
Business Combination, Consideration Transferred
Common stock, par value (usd per share)			$ 0.01