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Bank segment - Available-for-sale securities, narrative (Details) - USD ($) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Bank Subsidiary [Abstract] |  |  |  |
Proceeds from sale of available-for-sale investment securities | $ 169,200,000 | $ 0 | $ 169,157,000 | $ 0
Gross realized gains on available-for-sale securities | 9,300,000 | 0 | 9,300,000 | 0
Gross realized losses on available-for-sale securities | 0 | $ 0 | 0 | $ 0
Tax expense on realized gains | $ 2,500,000 |  | $ 2,500,000 |

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- Definition Debt Securities, Available-for-sale, Realized Gain (Loss), Expense (Benefit) + References No definition available. + Details
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- Definition Amount of unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
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