LONG-TERM DEBT AND FINANCING ARRANGEMENTS (Summary) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Long-term debt obligations
Long-term debt	$ 263,018	$ 243,673
Less current portion	62,837	64,143
Long-term debt, less current portion	200,181	179,530
Payments under long-term debt obligations
Due in one year or less	69,017
Due after one year through two years	42,954
Due after two years through three years	68,157
Due after three years through four years	20,346
Due after four years through five years	83,472
Total payments	283,946
Less amounts representing interest	20,928
Long-term debt	263,018	243,673
Credit Facility
Long-term debt obligations
Long-term debt	$ 70,000	70,000
Interest rate (as a percent)	2.70%
Payments under long-term debt obligations
Due in one year or less	$ 2,095
Due after one year through two years	2,327
Due after two years through three years	2,448
Due after three years through four years	2,529
Due after four years through five years	71,982
Total payments	81,381
Less amounts representing interest	11,381
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)	3.35%
Accounts receivable securitization program
Long-term debt obligations
Long-term debt	$ 45,000	35,000
Interest rate (as a percent)	2.10%
Payments under long-term debt obligations
Due in one year or less	$ 1,073
Due after one year through two years	1,222
Due after two years through three years	45,642
Total payments	47,937
Less amounts representing interest	2,937
Long-term debt	45,000	35,000
Notes payable
Long-term debt obligations
Long-term debt	$ 147,490	138,032
Weighted-average interest rate (as a percent)	2.50%
Payments under long-term debt obligations
Due in one year or less	$ 65,617
Due after one year through two years	39,167
Due after two years through three years	19,982
Due after three years through four years	17,809
Due after four years through five years	11,487
Total payments	154,062
Less amounts representing interest	6,572
Long-term debt	147,490	138,032
Capital lease obligations
Long-term debt obligations
Long-term debt	$ 528	641
Weighted-average interest rate (as a percent)	5.70%
Payments under long-term debt obligations
Due in one year or less	$ 232
Due after one year through two years	238
Due after two years through three years	85
Due after three years through four years	8
Due after four years through five years	3
Total payments	566
Less amounts representing interest	38
Long-term debt	$ 528	$ 641