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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Equity securities:
Net gains (losses) from equity securities sold	$ (1,061)	$ 4,218	$ 3,945	$ 6,240
Net gains (losses) from equity securities still held	(26,224)	8,707	(48,259)	5,541
Total net gains (losses) on equity securities	(27,285)	12,925	(44,314)	11,781
Available-for-sale debt securities:
Net gains (losses) on debt securities	(14,510)	267	(24,054)	2,379
Net gains (losses) on investment securities	$ (41,795)	$ 13,192	$ (68,368)	$ 14,160

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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).

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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
-Publisher FASB
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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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