LONG-TERM DEBT AND FINANCING ARRANGEMENTS - Securitization program (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Financing Arrangements
Long-term debt			$ 284,224	$ 323,519
Additional borrowings under accounts receivable securitization program			45,000
Outstanding letters of credit			12,300	12,800
Accounts receivable securitization borrowings
Financing Arrangements
Maximum borrowing capacity			125,000
Additional borrowing capacity that may be requested			25,000
Long-term debt				40,000
Additional borrowings under accounts receivable securitization program		$ 45,000
Repayment of accounts receivable securitization	$ 85,000
Outstanding letters of credit			11,700	$ 12,200
Remaining borrowing capacity			$ 113,300