CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 150,021	$ 149,805
Other comprehensive (loss) income, net of tax:
Change in unrealized investment gains and losses	(94,129)	(72,585)
Benefit plan adjustments	873	1,101
Other comprehensive (loss) income, net of tax	(93,256)	(71,484)
Comprehensive income	$ 56,765	$ 78,321