The following table provides detail of the plans’ net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction or billed to electric plant participants) (dollars in thousands):


			Pension Plans								Other Benefits Plans
	Three Months Ended June 30,	Six Months Ended June 30,	Three Months Ended June 30,				Six Months Ended June 30,
			2026		2025		2026		2025		2026		2025		2026		2025
Service cost-benefits earned during the period			$	11,684	$	11,127	$	23,783	$	22,076	$	2,140	$	2,059	$	4,377	$	4,041
Non-service costs (credits):
Interest cost on benefit obligation			37,292		38,584		74,904		77,560		4,931		5,070		9,910		10,172
Expected return on plan assets			(44,365)		(44,849)		(88,461)		(89,396)		(12,719)		(12,142)		(25,438)		(24,284)
Amortization of:
Prior service cost (credit)			151		—		302		—		—		—		—		(1,265)
Net actuarial loss (gain)			10,443		11,248		21,596		23,366		(2,746)		(2,965)		(5,446)		(5,864)
Net periodic benefit costs (credits)			$	15,205	$	16,110	$	32,124	$	33,606	$	(8,394)	$	(7,978)	$	(16,597)	$	(17,200)
Portion of costs (credits) charged to expense			$	8,262	$	9,365	$	17,780	$	19,826	$	(6,644)	$	(6,399)	$	(13,153)	$	(13,272)