OPERATING LEASES (Tables)

12 Months Ended

Dec. 31, 2016

OPERATING LEASES [Abstract]

Rental Expense from Continuing Operations under Nonmineral Operating Leases

in thousands	2016	2015	2014
Operating Leases
Minimum rentals	$        52,713	$       49,461	$       42,887
Contingent rentals (based principally on usage)	57,278	60,380	56,717
Total	$      109,991	$     109,841	$       99,604

Future Minimum Operating Lease Payments

in thousands
Future Minimum Operating Lease Payments
2017	$        31,017
2018	29,389
2019	25,132
2020	23,022
2021	21,312
Thereafter	119,602
Total	$      249,474