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Fair Value Disclosure (Narrative) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2020 | Jun. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | Dec. 31, 2019 | Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Realized gain (loss) on equity securities | $ 35 |  | $ 108 | $ 351 | $ 1,067 |  |
Investment in equity securities |  |  |  | 2,000 | 0 |  |
Level 1 | Fair value measurements, recurring |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Equity securities | 12,238 |  |  | 12,238 |  | $ 10,120 |
Realized gain (loss) on equity securities | (500) |  |  | (100) |  |  |
Bellaire | Level 1 | Fair value measurements, recurring |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Realized gain (loss) on equity securities | $ 500 |  | $ 100 | $ 400 | $ 1,100 |  |
Carrying Value | Level 1 | Fair value measurements, recurring |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Investment in equity securities |  | $ 2,000 |  |  |  |  |
Carrying Value | Bellaire | Level 1 | Fair value measurements, recurring |  |  |  |  |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |
Equity securities |  |  |  |  |  |  | $ 5,000

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