LONG-TERM DEBT AND FINANCING ARRANGEMENTS (Summary) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Long-term debt obligations
Long-term debt	$ 298,420	$ 291,675
Less current portion	50,197	54,075
Long-term debt, less current portion	248,223	237,600
Payments under long-term debt obligations
Due in one year or less	58,779
Due after one year through two years	55,830
Due after two years through three years	88,632
Due after three years through four years	33,068
Due after four years through five years	15,896
Due after five years	70,000
Total payments	322,205
Less amounts representing interest	23,785
Long-term debt	298,420	291,675
Credit Facility
Long-term debt obligations
Long-term debt	$ 70,000	70,000
Interest rate (as a percent)	3.20%
Payments under long-term debt obligations
Due in one year or less	$ 1,951
Due after one year through two years	1,687
Due after two years through three years	1,668
Due after three years through four years	1,694
Due after four years through five years	1,733
Due after five years	70,000
Total payments	78,733
Less amounts representing interest	8,733
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)	2.98%	3.10%
Accounts receivable securitization borrowings
Long-term debt obligations
Long-term debt	$ 40,000	$ 40,000
Interest rate (as a percent)	3.00%
Payments under long-term debt obligations
Due in one year or less	$ 1,023
Due after one year through two years	873
Due after two years through three years	40,000
Total payments	41,896
Less amounts representing interest	1,896
Long-term debt	40,000	40,000
Notes payable
Long-term debt obligations
Long-term debt	$ 188,326	181,409
Weighted-average interest rate (as a percent)	3.40%
Payments under long-term debt obligations
Due in one year or less	$ 55,721
Due after one year through two years	53,263
Due after two years through three years	46,961
Due after three years through four years	31,374
Due after four years through five years	14,163
Total payments	201,482
Less amounts representing interest	13,156
Long-term debt	188,326	181,409
Finance lease obligations
Long-term debt obligations
Long-term debt	$ 94	266
Weighted-average interest rate (as a percent)	5.30%
Payments under long-term debt obligations
Due in one year or less	$ 84
Due after one year through two years	7
Due after two years through three years	3
Total payments	94
Long-term debt	$ 94	$ 266