Segment Information - Selected Financial Information by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Net sales	$ 2,125.9	$ 2,000.1	$ 6,499.6	$ 5,687.1
Operating Income (Loss)	360.3	352.8	1,132.7	885.7
Non-operating pension income	3.6	5.0	10.9	14.8
Interest expense, net	(16.5)	(23.9)	(55.3)	(72.2)
Income before taxes	347.4	333.9	1,088.3	828.3
Trade
Segment Reporting Information [Line Items]
Net sales	2,125.9	2,000.1	6,499.6	5,687.1
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales	(42.9)	(40.9)	(125.4)	(113.2)
Operating Segments
Segment Reporting Information [Line Items]
Net sales	2,125.9	2,000.1	6,499.6	5,687.1
Segment Reconciling Items
Segment Reporting Information [Line Items]
Net sales	(42.9)	(40.9)	(125.4)	(113.2)
Packaging
Segment Reporting Information [Line Items]
Net sales	1,940.2	1,829.4	5,971.6	5,171.4
Operating Income (Loss)	359.2	365.2	1,141.3	940.3
Packaging | Trade
Segment Reporting Information [Line Items]
Net sales	1,935.1	1,825.0	5,956.8	5,159.3
Packaging | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales	5.1	4.4	14.8	12.1
Packaging | Operating Segments
Segment Reporting Information [Line Items]
Net sales	1,940.2	1,829.4	5,971.6	5,171.4
Paper
Segment Reporting Information [Line Items]
Net sales	165.3	150.3	468.6	457.1
Operating Income (Loss)	26.1	11.0	71.2	22.3
Paper | Trade
Segment Reporting Information [Line Items]
Net sales	165.3	150.3	468.6	457.0
Paper | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales			0.0	0.1
Paper | Operating Segments
Segment Reporting Information [Line Items]
Net sales	165.3	150.3	468.6	457.1
Corporate and Other
Segment Reporting Information [Line Items]
Net sales	20.4	20.4	59.4	58.6
Operating Income (Loss)	(25.0)	(23.4)	(79.8)	(76.9)
Corporate and Other | Trade
Segment Reporting Information [Line Items]
Net sales	25.5	24.8	74.2	70.8
Corporate and Other | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net sales	37.8	36.5	110.6	101.0
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Net sales	$ 63.3	$ 61.3	184.8	$ 171.8
Intersegment
Segment Reporting Information [Line Items]
Net sales			$ 0.0