Fair Value of Derivative and Other Financial Instruments - Investments in NDT and Gross Realized Losses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Equity securities:
Net gains (losses) from equity securities sold	$ 6,272	$ 2,792	$ 16,143	$ 1,947
Net gains (losses) from equity securities still held	(3,880)	1,142	(5,085)	8,619
Total net gains on equity securities	2,392	3,934	11,058	10,566
Available-for-sale debt securities:
Net gains (losses) on debt securities	(1,834)	(157)	7,498	(347)
Net gains on investment securities	$ 558	$ 3,777	$ 18,556	$ 10,219

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Amount of unrealized and realized gain (loss) on investment in debt and equity securities.

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

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Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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