Description of the Business and Summary of Significant Accounting Policies - Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Goodwill
Goodwill	$ 477,471,000	$ 477,471,000
Goodwill impairment loss	0	0	$ 0
Compensation expense for stock-based employee compensation plan	65,600,000	60,100,000	$ 69,200,000
Steel Operations
Goodwill
Goodwill	272,133,000
Aluminum Operations
Goodwill
Goodwill	14,000,000
Aluminum Operations | Restatement Adjustment
Goodwill
Goodwill	14,000,000
Metals Recycling Operations
Goodwill
Goodwill	189,413,000
Metals Recycling Operations | Restatement Adjustment
Goodwill
Goodwill	(14,000,000)
Metals Recycling Operations | OmniSource
Goodwill
Goodwill impaired accumulated impairment loss	346,800,000	$ 346,800,000
Steel Fabrication Operations
Goodwill
Goodwill	$ 1,925,000