Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2015

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment, at Cost

Property, plant and equipment, at cost, consist of the following at December 31, 2015 and 2014 (in thousands):

	Useful Lives (Years)	December 31,
		2015		2014
Land(a)	—	$	145,912	$	56,249
Land improvements	5 – 30	59,423		49,099
Buildings and improvements(a)	10 – 45	297,163		214,364
Machinery and equipment(b)	2 – 45	2,305,641		2,106,451
Long-term mineral rights and production equipment costs	7 – 60	652,871		85,888
Construction in progress	—	420,152		108,619
Total		$	3,881,162	$	2,620,670

(a) Includes Land under capital lease of $2.8 million and Buildings and improvements under capital lease of $9.9 million at December 31, 2015.

(b) Consists primarily of (1) short-lived production equipment components, office and building equipment and other equipment with estimated lives ranging 2 – 7 years, (2) production process equipment (intermediate components) with estimated lives ranging 8 – 19 years, (3) production process equipment (major unit components) with estimated lives ranging 20 – 29 years, and (4) production process equipment (infrastructure and other) with estimated lives ranging 30 – 45 years.