Postretirement Benefits - Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair value of plan assets:
Fair value of plan assets, beginning of year	$ 996,879	$ 829,866
Actual return on plan assets	8,034	105,631
Employer contributions	37,061	96,222
Benefits paid	(35,924)	(34,840)
Settlements	(4,001)	0
Fair value of plan assets, end of year	$ 1,002,049	$ 996,879