LONG-TERM DEBT AND FINANCING ARRANGEMENTS (Summary) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Long-term debt obligations
Long-term debt	$ 276,458	$ 291,675
Less current portion	48,809	54,075
Long-term debt, less current portion	227,649	237,600
Payments under long-term debt obligations
Due in one year or less	57,780
Due after one year through two years	47,102
Due after two years through three years	83,567
Due after three years through four years	99,600
Due after four years through five years	11,714
Total payments	299,763
Less amounts representing interest	23,305
Long-term debt	276,458	291,675
Credit Facility
Long-term debt obligations
Long-term debt	$ 70,000	70,000
Interest rate (as a percent)	3.70%
Payments under long-term debt obligations
Due in one year or less	$ 2,590
Due after one year through two years	2,383
Due after two years through three years	2,341
Due after three years through four years	70,629
Total payments	77,943
Less amounts representing interest	7,943
Long-term debt	70,000	$ 70,000
Credit Facility | Interest rate swap agreement
Long-term debt obligations
Amount of borrowings covered by the interest rate swap	$ 50,000
Effective fixed interest rate on hedged borrowings (as a percent)	3.10%	3.10%
Accounts receivable securitization borrowings
Long-term debt obligations
Long-term debt	$ 40,000	$ 40,000
Interest rate (as a percent)	3.40%
Payments under long-term debt obligations
Due in one year or less	$ 1,338
Due after one year through two years	1,220
Due after two years through three years	40,698
Total payments	43,256
Less amounts representing interest	3,256
Long-term debt	40,000	40,000
Notes payable
Long-term debt obligations
Long-term debt	$ 166,248	181,409
Weighted-average interest rate (as a percent)	3.50%
Payments under long-term debt obligations
Due in one year or less	$ 53,655
Due after one year through two years	43,493
Due after two years through three years	40,521
Due after three years through four years	28,971
Due after four years through five years	11,714
Total payments	178,354
Less amounts representing interest	12,106
Long-term debt	166,248	181,409
Finance lease obligations
Long-term debt obligations
Long-term debt	$ 210	266
Weighted-average interest rate (as a percent)	5.60%
Payments under long-term debt obligations
Due in one year or less	$ 197
Due after one year through two years	6
Due after two years through three years	7
Total payments	210
Long-term debt	$ 210	$ 266