CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 634,983	$ 446,093	$ 673,763
Other comprehensive income (loss), net of tax:
Change in unrealized investment gains and losses	(122,099)	133,616	173,910
Benefit plans adjustment	24,975	10,497	23,012
Other comprehensive income (loss), net of tax	(97,124)	144,113	196,922
Comprehensive income	$ 537,859	$ 590,206	$ 870,685