Retirement Plans, Other Changes in Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost	$ (326)	$ (325)	$ (148)
Amortization of actuarial loss (gain)	24,091	(51,745)	25,519
Income tax benefit (expense)	(6,304)	13,495	(7,803)
Other comprehensive income (loss) on defined benefit pension and postretirement obligations	17,432	(37,917)	$ 23,656
RAP
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain (loss)	24,228	(53,466)
Amortization of prior service cost	(250)	(250)
Amortization of actuarial loss (gain)	0	658
Income tax benefit (expense)	(6,327)	13,553
Other comprehensive income (loss) on defined benefit pension and postretirement obligations	17,650	(39,504)
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain (loss)	12	305
Amortization of prior service cost	(75)	(75)
Amortization of actuarial loss (gain)	(29)	0
Income tax benefit (expense)	23	(58)
Other comprehensive income (loss) on defined benefit pension and postretirement obligations	$ (68)	$ 171