Property, Plant and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2014

Property Plant And Equipment [Abstract]

Property, Plant and Equipment, Net

December 31

(add 000)	2014			2013
Land and land improvements	$	849,704		$	728,396
Mineral reserves and interests		990,438			461,587
Buildings		157,233			118,655
Machinery and equipment		3,568,342			2,575,340
Construction in progress		125,959			92,906
		5,691,676			3,976,884
Less allowances for depreciation, depletion and amortization		(2,288,906	)		(2,177,643	)
Total	$	3,402,770		$	1,799,241

Gross Asset Value and Related Allowance for Amortization for Machinery and Equipment Recorded under Capital Lease

The gross asset value and related allowance for amortization for machinery and equipment recorded under capital leases at December 31 were as follows:

(add 000)	2014			2013
Machinery and equipment under capital leases	$	25,775		$	10,341
Less allowance for amortization		(2,808	)		(104	)
Total	$	22,967		$	10,237