INCOME TAXES (Provision) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current provision (benefit):
Federal									$ (604)	$ 9,156	$ 18,063
State									(335)	165	23
Foreign									1,052	2,124	1,657
Current tax provision									113	11,445	19,743
Deferred provision (benefit):
Federal									8,161	12,914	1,575
State									1,354	3,589	3,366
Foreign									7	(68)	(249)
Deferred tax provision									9,522	16,435	4,692
Total provision (benefit) for income taxes	$ (488)	$ 7,615	$ 6,150	$ (3,642)	$ 1,878	$ 12,892	$ 12,942	$ 167	9,635	27,880	24,435
Components of the deferred tax provision or benefit
Amortization, depreciation, and basis differences for property, plant and equipment and other long-lived assets									12,182	21,098	3,579
Amortization of intangibles									(3,623)	(3,184)	(2,934)
Changes in reserves for workers’ compensation, third-party casualty, and cargo claims									362	(674)	(1,970)
Revenue recognition									1,862	7	361
Allowance for doubtful accounts									(295)	307	(501)
Foreign tax credit carryforward utilized										434	665
Nonunion pension and other retirement plans									3,861	(234)	(1,595)
Deferred compensation plans									203	541	350
Federal net operating loss carryforwards utilized									161	70	4,472
State net operating loss carryforwards utilized (generated)									(304)	623	2,812
State depreciation adjustments									(758)	(657)	(539)
Share-based compensation									(681)	(621)	959
Valuation allowance increase (decrease)									(61)	22	(696)
Leases									(1)	(969)	237
Other accrued expenses									(4,108)	1,256	(362)
Other									722	(1,584)	(146)
Deferred tax provision									$ 9,522	$ 16,435	$ 4,692