LONG-TERM DEBT AND FINANCING ARRANGEMENTS - Summary (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Long-term debt obligations
Long-term debt	$ 284,224	$ 323,519
Less current portion	67,105	57,305
Long-term debt, less current portion	$ 217,119	266,214
Weighted-average interest rate (as a percent)	2.90%
Payments under long-term debt obligations
2021	$ 73,386
2022	64,750
2023	48,892
2024	102,393
2025	9,576
Total payments	298,997
Less amounts representing interest	14,773
Long-term debt	284,224	323,519
Credit Facility
Long-term debt obligations
Long-term debt	$ 70,000	70,000
Interest rate (as a percent)	1.30%
Payments under long-term debt obligations
2021	$ 886
2022	914
2023	971
2024	70,823
Total payments	73,594
Less amounts representing interest	3,594
Long-term debt	70,000	70,000
Accounts receivable securitization borrowings
Long-term debt obligations
Long-term debt		40,000
Payments under long-term debt obligations
Long-term debt		40,000
Notes payable
Long-term debt obligations
Long-term debt	$ 214,216	213,504
Weighted-average interest rate (as a percent)	3.00%
Payments under long-term debt obligations
2021	$ 72,493
2022	63,835
2023	47,921
2024	31,570
2025	9,576
Total payments	225,395
Less amounts representing interest	11,179
Long-term debt	214,216	213,504
Finance lease obligations
Long-term debt obligations
Long-term debt	$ 8	15
Weighted-average interest rate (as a percent)	3.30%
Payments under long-term debt obligations
2021	$ 7
2022	1
Total payments	8
Long-term debt	$ 8	$ 15

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Represents aggregate future amounts due of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest.

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Represents amount of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest, due within one year of the latest balance sheet date presented.

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Represents amount of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest, due after four and within five years of the latest balance sheet date presented.

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Represents the interest amount by which the contractually required payments on capital leases and long-term debt are reduced to calculate the present value of the long-term debt and capital lease obligations.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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