COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2017

COMMITMENTS AND CONTINGENCIES [Abstract]

Commitments Due

	Unconditional
	Purchase
in thousands	Obligations
Property, Plant & Equipment
2018	$      134,458
Thereafter	0
Total	$      134,458
Noncapital (primarily transportation and electricity contracts)
2018	$        10,449
2019–2020	15,109
2021–2022	3,587
Thereafter	3,000
Total	$        32,145

Minimum Royalties Under Mineral Leases

	Mineral
in thousands	Leases
Minimum Royalties
2018	$        22,531
2019–2020	34,022
2021–2022	22,703
Thereafter	132,176
Total	$      211,432