Income Taxes - Federal Statutory Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income before income taxes	$ 102,937	$ 90,943	$ 82,324
Income Tax Statutory Rate Reconciliation [Abstract]
Income tax at federal statutory rate	21,617	19,098	17,288
Increase (decrease) in taxes attributable to:
State taxes, net of federal income tax benefit	6,488	6,001	5,328
Uncertain tax positions	(1,053)	(4,330)	1,483
Property flow-through	(14,793)	(9,045)	(13,091)
Reversal of excess deferred taxes recognized in regulatory liability	(3,227)	(3,625)	(3,885)
Pension flow-through	(530)	(597)	27
Stock-based compensation	192	(491)	(297)
Other items, net	276	(1,055)	1,643
Income tax expense	$ 8,970	$ 5,956	$ 8,496