Fair Value of Derivative and Other Financial Instruments - Investments in NDT and Gross Realized Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Equity securities:
Net gains from equity securities sold	$ 5,006	$ 2,022
Net (losses) from equity securities still held	(22,035)	(3,166)
Total net (losses) on equity securities	(17,029)	(1,144)
Available-for-sale debt securities:
Net gains (losses) on debt securities	(9,544)	2,112
Net gains (losses) on investment securities	$ (26,573)	$ 968

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

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

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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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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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