STOCKHOLDERS' EQUITY - AOCI Components (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Changes in accumulated other comprehensive income, net of tax, by component
Balances	$ 1,063,212	$ 983,172	$ 929,067	$ 898,134	$ 851,909	$ 828,593	$ 929,067	$ 828,593
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	(996)	(349)	1,624	(785)	678	804	279	697
Balances	1,126,292	1,063,212	983,172	961,043	898,134	851,909	1,126,292	961,043
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income, net of tax, by component
Balances	4,974	5,323	3,699	2,672	1,994	1,190	3,699	1,190
Other comprehensive income (loss) before reclassifications							701	997
Amounts reclassified from accumulated other comprehensive income							(422)	(300)
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	(996)	(349)	1,624	(785)	678	804	279	697
Balances	3,978	$ 4,974	5,323	1,887	$ 2,672	1,994	3,978	1,887
Unrecognized Net Periodic Benefit Credit
Changes in accumulated other comprehensive income, net of tax, by component
Balances			4,160			3,260	4,160	3,260
Amounts reclassified from accumulated other comprehensive income							(422)	(300)
OTHER COMPREHENSIVE INCOME (LOSS), net of tax							(422)	(300)
Balances	3,738			2,960			3,738	2,960
Interest Rate Swap
Changes in accumulated other comprehensive income, net of tax, by component
Balances			309			(1,198)	309	(1,198)
Other comprehensive income (loss) before reclassifications							2,383	869
OTHER COMPREHENSIVE INCOME (LOSS), net of tax							2,383	869
Balances	2,692			(329)			2,692	(329)
Foreign Currency Translation
Changes in accumulated other comprehensive income, net of tax, by component
Balances			$ (770)			$ (872)	(770)	(872)
Other comprehensive income (loss) before reclassifications							(1,682)	128
OTHER COMPREHENSIVE INCOME (LOSS), net of tax							(1,682)	128
Balances	$ (2,452)			$ (744)			$ (2,452)	$ (744)