OPERATING LEASES AND COMMITMENTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Leases and Commitments
Rental expense	$ 25,000	$ 30,200	$ 24,100
Future minimum rental commitments for all noncancelable operating leases
2016	14,697
2017	12,289
2018	10,338
2019	8,488
2020	7,016
Thereafter	10,487
Total	63,315
Land and structures (terminals)
Future minimum rental commitments for all noncancelable operating leases
2016	14,130
2017	12,116
2018	10,258
2019	8,424
2020	7,016
Thereafter	10,487
Total	62,431
Service, office, and other equipment
Future minimum rental commitments for all noncancelable operating leases
2016	567
2017	173
2018	80
2019	64
Total	$ 884