Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

Schedule of depreciable lives

Property, plant and equipment are stated at cost. Depreciation and amortization are computed using the straight-line method or the units-of-production (UOP) method. Depreciable lives are as follows:

	Years
Mobile and office equipment	3 to 12
Production facilities and related assets	3 to 25
Land improvements	10 to 20
Buildings	10 to 45