Postretirement Benefits - Pension Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair value of plan assets:
Fair value of plan assets, beginning of year	$ 1,140,243	$ 1,081,061
Actual return on plan assets	(304,005)	86,966
Employer contributions	25,764	1,245
Benefits paid	(32,136)	(29,029)
Fair value of plan assets, end of year	$ 829,866	$ 1,140,243