CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 157,977	$ 130,811	$ 461,049	$ 294,663
Other comprehensive income (loss), net of tax:
Change in unrealized investment gains and losses	(27,600)	33,712	(76,675)	104,308
Benefit plan adjustments	5,963	(11,347)	7,499	(9,239)
Other comprehensive income (loss), net of tax	(21,637)	22,365	(69,176)	95,069
Comprehensive income	$ 136,340	$ 153,176	$ 391,873	$ 389,732