CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 7,939	$ 25,044
Net unrealized holding gains on marketable securities:
Unrealized holding gains net of tax of ($3,277) and ($1,781), respectively	8,157	4,452
Reclassification adjustment for gains included in net income, net of tax of ($14) and $0 respectively	37	0
Net unrealized holding gains on marketable securities	8,194	4,452
Change in fair value of interest rate swaps, net of tax of $162 and $0, respectively	(409)	0
Defined benefit plan:
Actuarial reclassification adjustments for prior period service costs and actuarial losses included in net income, net of tax of ($99) and ($82), respectively	249	209
Other comprehensive income	8,034	4,661
Total comprehensive income	$ 15,973	$ 29,705