STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 159,830	$ 131,040	$ 448,285	$ 335,133
Other comprehensive income (loss), net of tax
Change in unrealized holding gains (losses) on available-for-sale securities	20,227	(5,902)	21,014	2,846
Pension and other postretirement plans	(1,538)	(2,742)	(6,048)	(8,226)
Total other comprehensive income (loss), net of tax	18,689	(8,644)	14,966	(5,380)
Comprehensive income	$ 178,519	$ 122,396	$ 463,251	$ 329,753