Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Statement of Operations (Details)

v3.10.0.1
Summary of Significant Accounting Policies - Statement of Operations (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]                      
Revenues $ 404.3 $ 429.9 $ 459.4 $ 471.8 $ 424.9 $ 359.4 $ 374.8 $ 419.5 $ 1,765.4 $ 1,578.6 $ 1,338.3
Cost of sales                 (1,578.7) (1,394.4) (1,156.6)
Gross profit 36.9 42.9 57.9 49.0 45.8 43.6 44.2 50.6 186.7 184.2 181.7
Selling, general and administrative expenses                 (92.7) (83.8) (82.8)
Operating income                 94.0 100.4 98.9
Interest expense, net                 (16.8) (17.6) (26.2)
Loss on extinguishment of debt     (0.5)     (0.2)     (0.5) (0.2) (23.4)
Other income (expense), net                 (0.8) 3.0 0.2
Income before provision for income taxes 8.8 16.8 29.1 21.2 19.3 19.0 24.6 22.7 75.9 85.6 49.5
Provision for income taxes                 (17.3) (33.9) (16.7)
Net income 6.7 14.9 21.1 15.9 5.8 12.4 15.8 17.7 58.6 51.7 32.8
Net income attributable to noncontrolling interest                 (0.4) (0.6) (0.6)
Net income attributable to Global Brass and Copper Holdings, Inc. $ 6.6 $ 14.8 $ 21.0 $ 15.8 $ 5.6 $ 12.3 $ 15.7 $ 17.5 $ 58.2 $ 51.1 $ 32.2
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:                      
Basic (in usd per share) $ 0.30 $ 0.67 $ 0.95 $ 0.72 $ 0.26 $ 0.56 $ 0.72 $ 0.81 $ 2.66 $ 2.35 $ 1.50
Diluted (in usd per share) $ 0.29 $ 0.66 $ 0.94 $ 0.71 $ 0.25 $ 0.56 $ 0.71 $ 0.79 $ 2.61 $ 2.31 $ 1.49
Weighted average common shares outstanding:                      
Basic (in shares)                 21.9 21.7 21.4
Diluted (in shares)                 22.3 22.1 21.6
Previously Reported [Member]                      
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]                      
Revenues                   $ 1,560.8 $ 1,338.5
Cost of sales                   (1,376.8) (1,156.9)
Gross profit                   184.0 181.6
Selling, general and administrative expenses                   (83.8) (82.8)
Operating income                   100.2 98.8
Interest expense, net                   (17.6) (26.2)
Loss on extinguishment of debt                   (0.2) (23.4)
Other income (expense), net                   3.0 0.2
Income before provision for income taxes                   85.4 49.4
Provision for income taxes                   (33.9) (16.6)
Net income                   51.5 32.8
Net income attributable to noncontrolling interest                   (0.6) (0.6)
Net income attributable to Global Brass and Copper Holdings, Inc.                   $ 50.9 $ 32.2
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:                      
Basic (in usd per share)                   $ 2.35 $ 1.50
Diluted (in usd per share)                   $ 2.30 $ 1.49
Weighted average common shares outstanding:                      
Basic (in shares)                   21.7 21.4
Diluted (in shares)                   22.1 21.6
Restatement Adjustment [Member] | Accounting Standards Update 2014-09 [Member]                      
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]                      
Revenues                   $ 17.8 $ (0.2)
Cost of sales                   (17.6) 0.3
Gross profit                   0.2 0.1
Selling, general and administrative expenses                   0.0 0.0
Operating income                   0.2 0.1
Interest expense, net                   0.0 0.0
Loss on extinguishment of debt                   0.0 0.0
Other income (expense), net                   0.0 0.0
Income before provision for income taxes                   0.2 0.1
Provision for income taxes                   0.0 (0.1)
Net income                   0.2 0.0
Net income attributable to noncontrolling interest                   0.0 0.0
Net income attributable to Global Brass and Copper Holdings, Inc.                   $ 0.2 $ 0.0
Net income attributable to Global Brass and Copper Holdings, Inc. per common share:                      
Basic (in usd per share)                   $ 0.00 $ 0.00
Diluted (in usd per share)                   $ 0.01 $ 0.00
Weighted average common shares outstanding:                      
Basic (in shares)                   0.0 0.0
Diluted (in shares)                   0.0 0.0