OPERATING LEASES (Tables)

12 Months Ended

Dec. 31, 2018

OPERATING LEASES [Abstract]

Rental Expense from Continuing Operations Under Nonmineral Operating Leases

in thousands	2018	2017	2016
Operating Leases
Minimum rentals	$        76,443	$       59,536	$       52,713
Contingent rentals (based principally on usage)	54,572	50,822	57,278
Total	$      131,015	$     110,358	$     109,991

Future Minimum Operating Lease Payments

in thousands
Future Minimum Operating Lease Payments
2019	$        47,979
2020	43,540
2021	35,732
2022	27,463
2023	19,707
Thereafter	195,104
Total	$      369,525