Segment Information, Net Sales by End Market Segment Applications (Details) - Fabricated Products - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net Sales:
Net sales	$ 343.2	$ 371.7
Aero/HS products
Net Sales:
Net sales	176.9	180.3
Automotive Extrusions
Net Sales:
Net sales	48.4	50.1
GE products
Net Sales:
Net sales	105.4	119.1
Other products
Net Sales:
Net sales	$ 12.5	$ 22.2