Segment Information (Detail) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net Sales	$ 457.4			$ 445.2	$ 1,415.8	$ 1,326.0
Income from operations	49.2			(2.4)	116.2	27.2
Other operating charges, net	(0.3)	$ 3.0	$ 8.5	(1.9)	(11.9)	(2.1)
Consumer Products
Segment Reporting Information [Line Items]
Net Sales	248.3			228.5	789.1	676.2
Income from operations	31.3			(4.4)	82.1	(8.3)
Pulp And Paperboard [Member]
Segment Reporting Information [Line Items]
Net Sales	209.1			216.6	626.6	649.7
Income from operations	32.8			17.1	91.6	80.1
Corporate
Segment Reporting Information [Line Items]
Income from operations	(14.6)			(13.2)	(45.6)	(42.5)
Retail tissue [Domain]
Segment Reporting Information [Line Items]
Net Sales	238.6			215.3	747.1	630.4
Paperboard [Domain]
Segment Reporting Information [Line Items]
Net Sales	208.0			215.4	623.1	644.6
Non-retail tissue [Domain]
Segment Reporting Information [Line Items]
Net Sales	6.9			12.4	31.0	43.2
Other [Domain]
Segment Reporting Information [Line Items]
Net Sales	$ 3.9			$ 2.1	$ 14.6	$ 7.9