Quarterly report pursuant to Section 13 or 15(d)

Revenue (Details)

v3.10.0.1
Revenue (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer $ 429.9 $ 359.4 $ 1,361.1 $ 1,153.7  
Contract with customer, liability, revenue recognized 0.0 0.0 0.4 0.0  
Building and Housing [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 143.8 115.6 457.7 354.5  
Automotive and Transportation [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 84.3 78.5 262.6 231.7  
Munitions [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 44.9 25.5 132.3 148.1  
Coinage [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 44.4 35.3 131.1 107.4  
Industrial Machinery and Equipment [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 35.9 35.1 113.0 105.2  
Electronic/Electrical Components [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 36.8 33.2 113.6 99.7  
Other Products and Services [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 39.8 $ 36.2 150.8 $ 107.1  
Accrued Liabilities [Member]          
Disaggregation of Revenue [Line Items]          
Customer advances, current $ 0.0   $ 0.0   $ 0.4