Divestitures, Discontinued Operations and Assets and Liabilities Held for Sale (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Inventories, net	$ 25.8	$ 31.3
Investment land	19.4	40.6
Other assets	0.6	1.3
Total current assets held for sale	45.8	73.2
Property, plant and equipment	87.2	124.5
Intangible assets, excluding goodwill	208.5	208.5
Operating lease right-of-use assets	6.1	12.1
Goodwill	31.9	31.9
Valuation allowance for loss on sale	(26.4)	(4.5)
Total noncurrent assets held for sale	307.3	372.5
Lease obligations	(1.3)	(4.5)
Total current liabilities held for sale	(1.3)	(4.5)
Lease obligations	(2.5)	(4.1)
Asset retirement obligations	(17.6)	(17.7)
Total noncurrent liabilities held for sale	(20.1)	(21.8)
Continuing Operations
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Investment land	19.4	40.6
Total current assets held for sale	19.4	40.6
Discontinued Operations
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Inventories, net	25.8	31.3
Other assets	0.6	1.3
Total current assets held for sale	26.4	32.6
Property, plant and equipment	87.2	124.5
Intangible assets, excluding goodwill	208.5	208.5
Operating lease right-of-use assets	6.1	12.1
Goodwill	31.9	31.9
Valuation allowance for loss on sale	(26.4)	(4.5)
Total noncurrent assets held for sale	307.3	372.5
Lease obligations	(1.3)	(4.5)
Total current liabilities held for sale	(1.3)	(4.5)
Lease obligations	(2.5)	(4.1)
Asset retirement obligations	(17.6)	(17.7)
Total noncurrent liabilities held for sale	$ (20.1)	$ (21.8)