Summary of Significant Accounting Policies - Business (Details)	12 Months Ended
	Dec. 31, 2016 item
Summary of Significant Accounting Policies
Minimum number of locations in which company operates metal service network	300
Number of states in which the company operates metal service center network	39
Number of countries in which entity operates outside the U.S.	12
Minimum number of metal products distributes by the company	100,000