CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 210,061	$ 184,213	$ 133,372
OTHER COMPREHENSIVE (LOSS) INCOME, NET OF TAX:
Unrealized (loss) gain on available-for-sale securities, net of tax of $65, $28 and $51, respectively	(7,745)	(233)	(100)
Employee benefit plan:
Actuarial gain (loss) on retirement plan, net of tax of $1,336, $3,569 and $988, respectively	5,971	13,620	(21,464)
Plan amendment cost, net of tax of $79, none and none, respectively	0	(283)	0
Amortization of prior service cost and actuarial loss for retirement plan included in net periodic pension costs, net of tax of $1,316, $723 and $713, respectively	2,037	4,719	2,556
Net change in employee benefit plan	8,008	18,056	(18,908)
Change in cumulative foreign currency translation adjustment	(480)	(39)	(14)
TOTAL OTHER COMPREHENSIVE INCOME (LOSS)	(217)	17,784	(19,022)
COMPREHENSIVE INCOME	$ 209,844	$ 201,997	$ 114,350