CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 51,520	$ 50,888	$ 92,821	$ 98,203
Other comprehensive (loss) income, net of tax
Unrealized gain (loss) on debt securities arising during the period	(101,078)	12,218	(243,479)	(18,750)
Change in retirement obligation	254	416	600	821
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(27)	0	(16)	0
Other comprehensive income (loss)	(100,851)	12,634	(242,895)	(17,929)
Comprehensive income (loss)	$ (49,331)	$ 63,522	$ (150,074)	$ 80,274