STOCKHOLDERS' EQUITY - AOCI (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income
Total after-tax amount	$ 1,126,292	$ 1,063,212	$ 983,172	$ 929,067	$ 961,043	$ 898,134	$ 851,909	$ 828,593
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income
Total pre-tax amount	5,359			4,977
Total after-tax amount	3,978	$ 4,974	$ 5,323	3,699	1,887	$ 2,672	$ 1,994	1,190
Unrecognized Net Periodic Benefit Credit
Accumulated Other Comprehensive Income
Total pre-tax amount	5,034			5,602
Total after-tax amount	3,738			4,160	2,960			3,260
Interest Rate Swap
Accumulated Other Comprehensive Income
Total pre-tax amount	3,646			419
Total after-tax amount	2,692			309	(329)			(1,198)
Foreign Currency Translation
Accumulated Other Comprehensive Income
Total pre-tax amount	(3,321)			(1,044)
Total after-tax amount	$ (2,452)			$ (770)	$ (744)			$ (872)