Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Weighted-average useful lives of structures and machinery and and equipment

The following table details the weighted-average useful lives of structures and machinery and equipment by reporting segment (numbers in years):

	Structures	Machinery and equipment
Engineered Products and Solutions	29	17
Global Rolled Products	31	21
Transportation and Construction Solutions	27	18

Weighted-average useful lives of software and other intangibles

The following table details the weighted-average useful lives of software and other intangible assets by reporting segment (numbers in years):

	Software	Other intangible assets
Engineered Products and Solutions	5	33
Global Rolled Products	5	9
Transportation and Construction Solutions	5	16