Investments (Tables)

12 Months Ended

Dec. 31, 2022

Schedule of Investments [Abstract]

Summary of debt and equity securities

The following tables summarize debt and equity securities at December 31, 2022 and 2021.

	Gross Unrealized
2022	Cost		Gains		Losses		Fair Value
	(dollars in thousands)
Equity	$	323,907	$	159,445	$	(8,949)	$	474,403
Debt		833,035		372		(46,369)		787,038
Other		10,445		20		(9)		10,456
Total	$	1,167,387	$	159,837	$	(55,327)	$	1,271,897

	Gross Unrealized
2021	Cost		Gains		Losses		Fair Value
	(dollars in thousands)
Equity	$	304,305	$	280,127	$	(4,682)	$	579,750
Debt		774,580		4,859		(7,001)		772,438
Other		19,102		—		(1)		19,101
Total	$	1,097,987	$	284,986	$	(11,684)	$	1,371,289

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, 2022 and 2021 are as follows:

	2022				2021
	Cost		Fair Value		Cost		Fair Value
	(dollars in thousands)
Due within one year	$	367,199	$	353,180	$	223,933	$	222,307
Due after one year through five years		293,523		275,073		371,060		368,574
Due after five years through ten years		66,255		62,576		62,679		62,639
Due after ten years		106,058		96,209		116,908		118,918
Total	$	833,035	$	787,038	$	774,580	$	772,438

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, 2022, 2021 and 2020:

	2022		2021		2020
	(dollars in thousands)
Gross realized gains	$	10,029	$	33,501	$	36,647
Gross realized losses		(31,979)		(19,985)		(16,868)
Proceeds from sales		301,128		913,600		756,513

Schedule of investments in associated companies

Investments in associated companies were as follows at December 31, 2022 and 2021:

	2022		2021
	(dollars in thousands)
National Rural Utilities Cooperative Finance Corporation (CFC)	$	24,081	$	24,081
CT Parts, LLC		6,574		7,049
Georgia Transmission Corporation		38,287		35,696
Georgia System Operations Corporation		7,750		6,500
Other		2,245		2,500
Total	$	78,937	$	75,826