Qualified Employee Benefit Plans - Valuation of our Retirement Plan Assets by Pricing Observability Levels (Details) - Retirement Plan - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	$ 101,376	$ 95,990	$ 130,939
Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	85,474	78,923
Level 1
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	23,267	40,592
Level 2
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	62,207	38,331
Level 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
NAV Expedient
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	15,902	17,067
Cash | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	944	1,441
Cash | Level 1
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	944	1,441
Cash | Level 2
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
Cash | Level 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
U.S. Treasury Strips | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	15,764	15,634
U.S. Treasury Strips | Level 1
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
U.S. Treasury Strips | Level 2
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	15,764	15,634
U.S. Treasury Strips | Level 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
Fixed income mutual funds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	2,271	2,149
Fixed income mutual funds | Level 1
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	2,271	2,149
Fixed income mutual funds | Level 2
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
Fixed income mutual funds | Level 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
Fixed income securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	46,443	22,478
Fixed income securities | Level 1
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0
Fixed income securities | Level 2
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	46,443	22,478
Fixed income securities | Level 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
Equity mutual funds | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	9,821	26,074
Equity mutual funds | Level 1
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	9,821	26,074
Equity mutual funds | Level 2
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
Equity mutual funds | Level 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	0
Equity securities | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	10,231	11,147
Equity securities | Level 1
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	10,231	10,928
Equity securities | Level 2
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	0	219
Equity securities | Level 3
Defined Benefit Plan, Assets [Abstract]
Total assets measured at fair value	$ 0	$ 0