The tables below detail assets and liabilities measured at fair value on a recurring basis at March 31, 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
	March 31, 2025		(Level 1)		(Level 2)		(Level 3)
	(dollars in thousands)
Nuclear decommissioning trust funds:
Domestic equity	$	234,410	$	234,410	$	—	$	—

Corporate bonds and debt	87,115		—		86,529		586
US Treasury securities	55,750		55,750		—		—
Mortgage backed securities	71,984		—		71,984		—
Domestic mutual funds	89,061		89,061		—		—
Municipal bonds	8,099		—		8,099		—
Federal agency securities	9,243		—		9,243		—
Non-US Gov't bonds & private placements	4,545		—		4,545		—
International mutual funds	153,135		—		153,135		—

Other	9,673		9,673		—		—
Long-term investments:

Corporate bonds and debt	22,432		—		22,432		—
US Treasury securities	26,358		26,358		—		—
Mortgage backed securities	21,551		—		21,551		—
Domestic mutual funds	387,612		387,612		—		—

Treasury STRIPS	134,822		—		134,822		—
Non-US Gov't bonds & private placements	2,744		—		2,744		—
International mutual funds	42,439		—		42,439		—
Other	603		603		—		—
Short-term investments: Treasury STRIPS	119,860		—		119,860		—
Natural gas swaps	59,792		—		59,792		—


	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		—