ACQUISITIONS - Schedule of preliminary valuation of identifiable assets acquired and liabilities assumed (Details) - USD ($) $ in Millions				3 Months Ended	8 Months Ended	12 Months Ended
	Jan. 31, 2020	Jun. 11, 2019	Feb. 11, 2019	Jan. 31, 2020	Jan. 31, 2020	Jan. 31, 2020
Tholu B.V.
Fair value of consideration transferred
Cash consideration	$ 25.1	$ 25.1
Cash consideration, measurement period adjustments					$ 0.0
Deferred payments	29.2	29.2
Deferred Payments, measurement period adjustments					0.0
Cash received	(2.1)	(2.1)
Cash Received, measurement period adjustments					0.0
Total consideration	52.2	52.2
Total consideration, measurement period adjustments					0.0
Recognized amounts of identifiable assets acquired and liabilities assumed
Accounts receivable	7.3	7.3		$ 7.3	7.3	$ 7.3
Accounts receivable, measurement period adjustments					0.0
Inventories	3.4	3.0		3.4	3.4	3.4
Inventories, measurement period adjustments					0.4
Intangibles	24.1	24.1		24.1	24.1	24.1
Intangibles, measurement period adjustments					0.0
Properties, plants and equipment	6.4	6.4		6.4	6.4	6.4
Properties, plants and equipment, measurement period adjustments					0.0
Other assets	1.2	1.2		1.2	1.2	1.2
Other assets, measurement period adjustments					0.0
Total assets acquired	42.4	42.0		42.4	42.4	42.4
Total assets acquired, measurement period adjustments					0.4
Accounts payable	(4.0)	(4.0)		(4.0)	(4.0)	(4.0)
Accounts payable, measurement period adjustments					0.0
Capital lease obligations	(1.7)	(1.7)		(1.7)	(1.7)	(1.7)
Capital Lease Obligations, measurement period adjustments					0.0
Long-term deferred tax liability	(5.8)	(5.4)		(5.8)	(5.8)	(5.8)
Long-term deferred tax liability, measurement period adjustments					(0.4)
Other long-term liabilities	(1.0)	(1.0)		(1.0)	(1.0)	(1.0)
Other long-term liabilities, measurement period adjustments					0.0
Total liabilities assumed	(12.5)	(12.1)		(12.5)	(12.5)	(12.5)
Total liabilities assumed, measurement period adjustments					(0.4)
Total identifiable net assets	29.9	29.9		29.9	29.9	29.9
Total identifiable net assets, measurement period adjustments					0.0
Goodwill	22.3	$ 22.3		22.3	22.3	22.3
Increase (decrease) in goodwill, measurement period adjustments					0.0
Caraustar
Fair value of consideration transferred
Cash consideration			$ 1,834.9	1,834.9
Cash consideration, measurement period adjustments						0.0
Recognized amounts of identifiable assets acquired and liabilities assumed
Accounts receivable	147.0		147.0	147.0	147.0	147.0
Accounts receivable, measurement period adjustments						0.0
Inventories	99.5		103.9	99.5	99.5	99.5
Inventories, measurement period adjustments						(4.4)
Prepaid and other current assets	12.2		21.5	12.2	12.2	12.2
Prepaid and other current assets, measurement period adjustments						(9.3)
Intangibles	725.5		717.1	725.5	725.5	725.5
Intangibles, measurement period adjustments						8.4
Other long-term assets	6.4		1.3	6.4	6.4	6.4
Other long term assets measurement period adjustments						5.1
Properties, plants and equipment	502.9		521.3	502.9	502.9	502.9
Properties, plants and equipment, measurement period adjustments						(18.4)
Total assets acquired	1,493.5		1,512.1	1,493.5	1,493.5	1,493.5
Total assets acquired, measurement period adjustments						(18.6)
Accounts payable	(99.5)		(99.5)	(99.5)	(99.5)	(99.5)
Accounts payable, measurement period adjustments						0.0
Accrued payroll and employee benefits	(49.3)		(42.9)	(49.3)	(49.3)	(49.3)
Accrued payroll and employee benefits, measurement period adjustments						6.4
Other current liabilities	(17.3)		(21.8)	(17.3)	(17.3)	(17.3)
Other current liabilities, measurement period adjustments						4.5
Long-term deferred tax liability	(138.8)		(185.7)	(138.8)	(138.8)	(138.8)
Long-term deferred tax liability, measurement period adjustments						46.9
Pension and postretirement obligations	(67.1)		(67.1)	(67.1)	(67.1)	(67.1)
Pension and postretirement obligations, measurement period adjustments						0.0
Other long-term liabilities	(20.0)		(12.7)	(20.0)	(20.0)	(20.0)
Other long-term liabilities, measurement period adjustments						(7.3)
Total liabilities assumed	(392.0)		(429.7)	(392.0)	(392.0)	(392.0)
Total liabilities assumed, measurement period adjustments						37.7
Total identifiable net assets	1,101.5		1,082.4	1,101.5	1,101.5	1,101.5
Total identifiable net assets, measurement period adjustments						19.1
Goodwill	$ 733.4		$ 752.5	$ 733.4	$ 733.4	733.4
Increase (decrease) in goodwill, measurement period adjustments						$ (19.1)