Acquisitions (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2020	Dec. 31, 2019
Allocation of the total purchase price of the acquisitions to the fair value of the assets acquired and liabilities assumed
Goodwill	$ 1,923.7	$ 2,003.8
Fry Steel
Acquisitions
Sales since acquisition date	43.8
Allocation of the total purchase price of the acquisitions to the fair value of the assets acquired and liabilities assumed
Cash		17.1
Accounts receivable		5.7
Inventories		39.3
Property, plant and equipment		29.4
Goodwill		54.1
Intangible assets subject to amortization		26.0
Intangible assets not subject to amortization		30.3
Other current and long-term assets		0.3
Total assets acquired		202.2
Other current and long-term liabilities		8.3
Total liabilities assumed		8.3
Net assets acquired		$ 193.9
Fry Steel \| Trade names
Allocation of the total purchase price of the acquisitions to the fair value of the assets acquired and liabilities assumed
Intangible assets not subject to amortization	30.3
Fry Steel \| Customer relationships
Summary purchase price allocation information for all acquisitions
Intangible assets acquired subject to amortization	$ 26.0
Weighted average lives of identifiable intangible assets	10 years

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