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Debt Securities Available-for-Sale - Narrative (Details) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 USD ($) security | Jun. 30, 2019 USD ($) | Jun. 30, 2020 USD ($) security | Jun. 30, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Debt securities, available-for-sale, restricted | $ 584,200,000 |  | $ 584,200,000 |
Proceeds from sale of debt securities available-for-sale | 12,600,000 | $ 5,200,000 | 12,623,000 | $ 34,442,000
Debt securities, available-for-sale, realized gain | 74,000 | 59,000 | 74,000 | 214,000
Debt securities, available-for-sale, realized loss | 1,000 | 0 | 14,000 | 0
Debt securities, trading, realized gain (loss) | 1,600,000 | 343,000 | (366,000) | 1,400,000
Other-than-temporary impairment loss, debt securities, available for sale, recognized in earnings | $ 0 | $ 0 | $ 0 | $ 0
Real Estate Mortgage Investment Conduits (REMICs) | GSE | Pass Through |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Number of debt securities, unrealized loss position longer than 12 months | security | 12 |  | 12 |
Real Estate Mortgage Investment Conduits (REMICs) | GSE | Non Pass Through |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Number of debt securities, unrealized loss position longer than 12 months | security | 4 |  | 4 |
Number of debt securities, unrealized loss position less than 12 months | security | 10 |  | 10 |
Real Estate Mortgage Investment Conduits (REMICs) | Non-GSE |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Number of debt securities, unrealized loss position longer than 12 months | security | 1 |  | 1 |
Real Estate Mortgage Investment Conduits (REMICs) | Municipal bonds |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Number of debt securities, unrealized loss position less than 12 months | security | 2 |  | 2 |

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- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without an allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922888-210455 + Details
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- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without an allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922888-210455 + Details
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- Definition Amount of realized gain 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://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563 + Details
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- Definition Amount of realized 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://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27357-111563 + Details
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- Definition Amount of restricted 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://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
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- Definition Amount of other-than-temporary impairment (OTTI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), recognized in earnings. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 8A -URI http://asc.fasb.org/extlink&oid=121553693&loc=SL6284422-111562 + Details
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