The tables below detail assets and liabilities measured at fair value on a recurring basis at June 30, 2025 and December 31, 2024.


	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	June 30, 2025		(Level 1)		(Level 2)		(Level 3)
	(dollars in thousands)
Nuclear decommissioning trust funds:
Domestic equity	$	260,203	$	260,203	$	—	$	—

Corporate bonds and debt	90,658		—		90,138		520
US Treasury securities	65,285		65,285		—		—
Mortgage backed securities	65,726		—		65,726		—
Domestic mutual funds	101,986		101,986		—		—
Municipal bonds	9,542		—		9,542		—
Federal agency securities	9,099		—		9,099		—
Non-US Gov't bonds & private placements	6,237		—		6,237		—
International mutual funds	172,645		—		172,645		—

Other	3,099		3,099		—		—
Long-term investments:

Corporate bonds and debt	23,346		—		23,346		—
US Treasury securities	29,616		29,616		—		—
Mortgage backed securities	20,573		—		20,573		—
Domestic mutual funds	386,250		386,250		—		—

Treasury STRIPS	114,622		—		114,622		—
Non-US Gov't bonds & private placements	3,119		—		3,119		—
International mutual funds	47,659		—		47,659		—
Other	715		715		—		—
Short-term investments: Treasury STRIPS	90,269		—		90,269		—
Natural gas swaps	36,027		—		36,027		—


	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	December 31, 2024		(Level 1)		(Level 2)		(Level 3)
	(dollars in thousands)
Nuclear decommissioning trust funds:
Domestic equity	$	245,313	$	245,313	$	—	$	—

Corporate bonds and debt	82,316		—		82,309		7
US Treasury securities	53,806		53,806		—		—
Mortgage backed securities	70,193		—		70,193		—
Domestic mutual funds	95,175		95,175		—		—
Municipal bonds	3,375		—		3,375		—
Federal agency securities	8,487		—		8,487		—
Non-US Gov't bonds & private placements	3,319		—		3,319		—
International mutual funds	4,228		—		4,228		—
Money Market	138,553		138,553		—		—
Other	16,859		16,859		—		—
Long-term investments:

Corporate bonds and debt	20,972		—		20,972		—
US Treasury securities	25,654		25,654		—		—
Mortgage backed securities	20,232		—		20,232		—
Domestic mutual funds	394,595		394,595		—		—

Treasury STRIPS	142,199		—		142,199		—
Non-US Gov't bonds & private placements	1,805		—		1,805		—
International mutual funds	39,340		—		39,340		—
Other	369		369		—		—
Short-term investments: Treasury STRIPS	124,572		—		124,572		—
Natural gas swaps	28,624		—		28,624		—