Discontinued Operations - Schedule of Assets and Liabilities Held-for-Sale (Details) - USD ($) $ in Millions		Sep. 30, 2023	Dec. 31, 2022
Current assets:
Current assets held-for-sale	[1]	$ 102.5	$ 107.2
Current liabilities:
Current liabilities held-for-sale	[1]	34.4	43.8
Disposal Group, Held-for-sale, Not Discontinued Operations | Aluminum Products Business
Current assets:
Accounts receivable, net		29.2	24.9
Inventories, net		20.5	30.2
Other current assets		1.8	1.2
Current assets held-for-sale		51.5	56.3
Property, plant and equipment, net		47.9	46.1
Operating lease right-of-use assets		3.1	4.8
Long-term assets held-for-sale		51.0	50.9
Total assets held-for-sale		102.5	107.2
Current liabilities:
Trade accounts payable		19.9	22.8
Current portion of finance lease liabilities		1.7	2.4
Current portion of operating lease liabilities		1.4	2.3
Other accrued expenses		7.7	10.7
Current liabilities held-for-sale		30.7	38.2
Long-term finance lease liabilities		2.0	3.1
Long-term operating lease liabilities		1.7	2.5
Long-term liabilities held-for-sale		3.7	5.6
Total liabilities held-for-sale		$ 34.4	$ 43.8

[1] Our continuing operations exclude the results of our Aluminum Products business unit, which is held-for-sale as of September 30, 2023 and December 31, 2022 and presented in discontinued operations for all periods presented.