Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net Income	$ 286,405	$ 655,892	$ 466,979
Actuarially Determined Long-Term Liability Adjustments:
Amortization of Prior Service Credits (net of tax: $538, $537, $561)	(1,867)	(1,868)	(1,844)
Recognized Net Actuarial Loss (Gain) (net of tax: ($982), $512, ($2,459))	3,406	(1,782)	8,076
Curtailment Gain Recognized (net of tax: $49, $—, $—)	(168)	0	0
Other Comprehensive Gain before Reclassifications (net of tax: ($3,792), ($1,232), ($30,516))	13,157	4,150	99,164
Available-for-Sale Securities:
Unrealized (Loss) Gain on Investments in Available-for-Sale Securities (net of tax: $12, ($23), $—)	(41)	80	0
Derivative Instruments:
Unrealized Gain on Cash Flow Hedges (net of tax: $—, $—, ($116))	0	0	401
Other Comprehensive Income	14,487	580	105,797
Comprehensive Income	$ 300,892	$ 656,472	$ 572,776