Quarterly report pursuant to Section 13 or 15(d)

Revenue (Details)

v3.10.0.1
Revenue (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer $ 459.4 $ 374.8 $ 931.2 $ 794.3  
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 156.3 114.2 313.9 238.9  
Automotive and Transportation [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 89.4 75.8 178.3 153.2  
Munitions [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 41.1 49.2 87.4 122.6  
Coinage [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 41.5 32.1 86.7 72.1  
Industrial Machinery and Equipment [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 36.2 33.5 77.1 70.1  
Electronic/Electrical Components [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 37.7 33.7 76.8 66.5  
Other Products and Services [Member]          
Disaggregation of Revenue [Line Items]          
Revenue from contract with customer 57.2 $ 36.3 111.0 $ 70.9  
Accrued Liabilities [Member]          
Disaggregation of Revenue [Line Items]          
Customer advances, current $ 0.0   $ 0.0   $ 0.4