Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Equipment

	(in thousands) December 31,
	2017			2016
Land and improvements	$	639,878		$	602,218
Buildings and improvements		1,249,350			1,169,064
Machinery and equipment		10,937,416			10,524,030
Proved oil and gas properties		556,507			551,019
Leasehold interest in unproved oil and gas properties		165,000			165,000
Construction in process and equipment deposits		241,820			224,677
		13,789,971			13,236,008
Less accumulated depreciation		(8,696,824	)		(8,157,358	)
	$	5,093,147		$	5,078,650