Quarterly report pursuant to Section 13 or 15(d)

Segment Information - Reconciliation of Adjusted EBITDA to Income Before Provision for Income Taxes (Detail)

v3.10.0.1
Segment Information - Reconciliation of Adjusted EBITDA to Income Before Provision for Income Taxes (Detail) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Segment Reporting Information [Line Items]        
Net sales $ 459.4 $ 374.8 $ 931.2 $ 794.3
Depreciation expense (5.2) (4.5) (10.3) (9.0)
Amortization expense (0.1) 0.0 (0.2) 0.0
Interest expense, net (4.3) (4.7) (8.6) (9.4)
Net income attributable to noncontrolling interest 0.1 0.1 0.2 0.3
Unrealized (loss) gain on derivative contracts (b) 1.8 (0.6) (0.6) (1.4)
Refinancing costs (c) (1.6) 0.0 (1.6) 0.0
Lower of cost or market adjustment to inventory (d) 0.2 (0.7) 1.1 0.1
Share-based compensation expense (e) (1.4) (1.8) (3.1) (4.3)
Step-up costs from acquisition accounting 0.0 0.0 (0.2) 0.0
Income before provision for income taxes 29.1 24.6 50.3 47.3
Insurance recoveries   4.4   7.4
Intersegment [Member]        
Segment Reporting Information [Line Items]        
Net sales 22.5 20.1 43.9 44.2
Operating Segments [Member]        
Segment Reporting Information [Line Items]        
Adjusted EBITDA 44.6 36.6 82.9 72.0
Corporate and Other [Member]        
Segment Reporting Information [Line Items]        
Adjusted EBITDA (5.0) 0.2 (9.3) (1.0)
Olin Brass [Member]        
Segment Reporting Information [Line Items]        
Net sales 175.8 158.8 354.5 349.6
Olin Brass [Member] | Intersegment [Member]        
Segment Reporting Information [Line Items]        
Net sales 22.4 20.0 43.8 44.0
Olin Brass [Member] | Operating Segments [Member]        
Segment Reporting Information [Line Items]        
Adjusted EBITDA 20.1 14.4 34.1 26.9
Chase Brass [Member]        
Segment Reporting Information [Line Items]        
Net sales 159.5 141.1 331.1 295.1
Chase Brass [Member] | Intersegment [Member]        
Segment Reporting Information [Line Items]        
Net sales 0.0 0.0 0.0 0.1
Chase Brass [Member] | Operating Segments [Member]        
Segment Reporting Information [Line Items]        
Adjusted EBITDA 18.4 17.9 37.0 38.3
A.J. Oster [Member]        
Segment Reporting Information [Line Items]        
Net sales 124.1 74.9 245.6 149.6
A.J. Oster [Member] | Intersegment [Member]        
Segment Reporting Information [Line Items]        
Net sales 0.1 0.1 0.1 0.1
A.J. Oster [Member] | Operating Segments [Member]        
Segment Reporting Information [Line Items]        
Adjusted EBITDA $ 6.1 $ 4.3 $ 11.8 $ 6.8