The tables below detail assets and liabilities measured at fair value on a recurring basis at June 30, 2026 and December 31, 2025.


	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	June 30, 2026		(Level 1)		(Level 2)		(Level 3)
	(dollars in thousands)
Nuclear decommissioning trust funds:
Domestic equity	$	279,655	$	279,655	$	—	$	—

Corporate bonds and debt	119,822		—		119,642		180
US Treasury securities	85,160		85,160		—		—
Mortgage backed securities	62,722		—		62,722		—
Domestic mutual funds	132,450		132,450		—		—
Municipal bonds	3,764		—		3,764		—
Federal agency securities	8,093		—		8,093		—
Non-US Gov't bonds & private placements	19,756		—		19,756		—
International mutual funds	206,888		—		206,888		—

Other	15,137		15,137
Long-term investments:

Corporate bonds and debt	30,021		—		30,021		—
US Treasury securities	44,025		44,025		—		—
Mortgage backed securities	24,810		—		24,810		—
Domestic mutual funds	434,624		434,624		—		—

Treasury STRIPS	53,584		—		53,584		—
Non-US Gov't bonds & private placements	3,039		—		3,039		—
International mutual funds	55,829		—		55,829		—
Other	412		412		—		—
Short-term investments: Treasury STRIPS	66,161		—		66,161		—
Natural gas swaps	15,176		—		15,176		—


	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	December 31, 2025		(Level 1)		(Level 2)		(Level 3)
	(dollars in thousands)
Nuclear decommissioning trust funds:
Domestic equity	$	254,191	$	254,191	$	—	$	—

Corporate bonds and debt	108,799		—		107,808		991
US Treasury securities	85,520		85,520		—		—
Mortgage backed securities	65,814		—		65,814		—
Domestic mutual funds	109,307		109,307		—		—
Municipal bonds	6,627		—		6,627		—
Federal agency securities	9,082		—		9,082		—
Non-US Gov't bonds & private placements	14,234		—		14,234		—
International mutual funds	180,112		—		180,112		—

Other	21,537		21,537		—		—
Long-term investments:

Corporate bonds and debt	27,967		—		27,967		—
US Treasury securities	36,716		36,716		—		—
Mortgage backed securities	28,996		—		28,996		—
Domestic mutual funds	430,593		430,593		—		—

Treasury STRIPS	76,392		—		76,392		—
Non-US Gov't bonds & private placements	3,294		—		3,294		—
International mutual funds	48,935		—		48,935		—
Other	372		372		—		—
Short-term investments: Treasury STRIPS	80,164		—		80,164		—
Natural gas swaps	10,642		—		10,642		—