Retirement Plans, Summary of Funded Status at End of Year (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Plan [Member]
Funded status at end of year [Abstract]
Fair value of plan assets	$ 341,061	$ 430,821	$ 395,137
Benefit obligations	(339,509)	(495,272)	(508,694)
Funded status and amount recognized at end of year	(1,552)	(64,451)
SERP [Member]
Funded status at end of year [Abstract]
Fair value of plan assets	0	0	0
Benefit obligations	(833)	(1,033)	(1,174)
Funded status and amount recognized at end of year	(833)	(1,033)
Other Postretirement Benefits [Member]
Funded status at end of year [Abstract]
Fair value of plan assets	0	0	0
Benefit obligations	(432)	(582)	$ (629)
Funded status and amount recognized at end of year	$ (432)	$ (582)