Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
NET SALES:	$ 1,731.0	$ 1,605.0	$ 3,375.0	$ 3,200.0
NET SALES:	1,737.0	1,611.0	3,386.0	3,210.0
(LOSS) INCOME FROM OPERATIONS:	95.0	115.0	203.0	275.0
DEPRECIATION AND AMORTIZATION:	117.0	122.0	234.0	236.0
Corporate/Other/Eliminations
Segment Reporting Information [Line Items]
NET SALES:	44.0	40.0	81.0	70.0
(LOSS) INCOME FROM OPERATIONS:	(22.0)	(28.0)	(28.0)	(52.0)
DEPRECIATION AND AMORTIZATION:	9.0	5.0	15.0	11.0
Paperboard Mills | Operating Segments
Segment Reporting Information [Line Items]
NET SALES:	244.0	234.0	481.0	503.0
(LOSS) INCOME FROM OPERATIONS:	(18.0)	(35.0)	(45.0)	(58.0)
DEPRECIATION AND AMORTIZATION:	56.0	67.0	114.0	126.0
Americas Paperboard Packaging | Operating Segments
Segment Reporting Information [Line Items]
NET SALES:	1,237.0	1,154.0	2,406.0	2,277.0
(LOSS) INCOME FROM OPERATIONS:	108.0	157.0	229.0	352.0
DEPRECIATION AND AMORTIZATION:	41.0	41.0	83.0	80.0
Europe Paperboard Packaging | Operating Segments
Segment Reporting Information [Line Items]
NET SALES:	212.0	183.0	418.0	360.0
(LOSS) INCOME FROM OPERATIONS:	27.0	21.0	47.0	33.0
DEPRECIATION AND AMORTIZATION:	$ 11.0	$ 9.0	$ 22.0	$ 19.0