CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 203,011	$ 210,061	$ 184,213
OTHER COMPREHENSIVEINCOME (LOSS), NET OF TAX:
Unrealized gain (loss) on available-for-sale securities, net of tax of ($351), none and $65, respectively	8,745	(7,745)	(233)
Employee benefit plan:
Actuarial gain on retirement plan, net of tax of ($2,168), ($1,667) and ($1,336), respectively	7,207	5,971	13,620
Plan amendment cost, net of tax of none, none and $79, respectively	0	0	(283)
Amortization of prior service cost and actuarial loss for retirement plan included in net periodic pension costs net of tax of ($299), ($569) and ($1,316), respectively	996	2,037	4,719
Net change in employee benefit plan	8,203	8,008	18,056
Change in cumulative foreign currency translation adjustment	418	(480)	(39)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)	17,366	(217)	17,784
COMPREHENSIVE INCOME	$ 220,377	$ 209,844	$ 201,997