Investments (Tables)

12 Months Ended

Dec. 31, 2024

Schedule of Investments [Abstract]

Summary of debt and equity securities

The following tables summarize debt and equity securities at December 31, 2024 and 2023.

	(dollars in thousands)
	Gross Unrealized
2024	Cost		Gains		Losses		Fair Value
Equity	$	259,554	$	231,815	$	(6,385)	$	484,984
Debt	864,575		3,209		(17,336)		850,448
Other	155,802		224		(96)		155,930
Total	$	1,279,931	$	235,248	$	(23,817)	$	1,491,362

	(dollars in thousands)
	Gross Unrealized
2023	Cost		Gains		Losses		Fair Value
Equity	$	344,669	$	246,795	$	(5,549)	$	585,915
Debt	908,316		3,938		(25,181)		887,073
Other	2,889		61		(36)		2,914
Total	$	1,255,874	$	250,794	$	(30,766)	$	1,475,902

Schedule of contractual maturities of debt securities

The contractual maturities of debt securities, which are included in the estimated fair value table above, at December 31, 2024 and 2023 are as follows:

	(dollars in thousands)
	2024				2023
	Cost		Fair Value		Cost		Fair Value
Due within one year	$	489,744	$	488,062	$	486,602	$	477,726
Due after one year through five years	188,519		185,714		267,690		260,193
Due after five years through ten years	63,526		62,123		47,804		47,416
Due after ten years	122,785		114,549		106,220		101,738
Total	$	864,574	$	850,448	$	908,316	$	887,073

Summary of realized gains and losses and proceeds from sales of securities

The following table summarizes the realized gains and losses and proceeds from sales of securities for the years ended December 31, 2024, 2023 and 2022:

	(dollars in thousands)
	2024		2023		2022
Gross realized gains	$	101,549	$	15,518	$	10,029
Gross realized losses	(11,193)		(8,564)		(31,979)
Proceeds from sales	1,484,525		720,186		301,128

Schedule of investments in associated companies

Investments in associated companies were as follows at December 31, 2024 and 2023:

	(dollars in thousands)
	2024		2023
National Rural Utilities Cooperative Finance Corporation (CFC)	$	23,983	$	24,068
CT Parts, LLC	6,561		6,568
Georgia Transmission Corporation	44,936		40,806
Georgia System Operations Corporation	7,250		6,500
Other	3,990		4,191
Total	$	86,720	$	82,133