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Securities Available for sale, Unrealized Loss Position, Fair Value (Details) $ in Thousands | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($)
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Available for sale, Unrealized Loss Position [Line Items] |  |
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | 77 | 203
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 1,143,562 | $ 2,182,644
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 438,846 | 897,351
Available for sale securities, Unrealized Loss Position, Fair Value | 1,582,408 | 3,079,995
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 8,197 | 10,928
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 642 | 9,358
Available for sale securities, Unrealized Loss Position, Accumulated Loss | 8,839 | $ 20,286
Debt Securities, Available-for-sale, Allowance for Credit Loss | $ 0 |
Municipal securities [Member] |  |
Available for sale, Unrealized Loss Position [Line Items] |  |
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | 1 | 0
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 6,166 | $ 0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 0 | 0
Available for sale securities, Unrealized Loss Position, Fair Value | 6,166 | 0
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 5 | 0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Available for sale securities, Unrealized Loss Position, Accumulated Loss | $ 5 | $ 0
Residential agency mortgage-backed securities [Member] |  |
Available for sale, Unrealized Loss Position [Line Items] |  |
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | 38 | 133
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 786,890 | $ 1,352,597
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 160,747 | 686,002
Available for sale securities, Unrealized Loss Position, Fair Value | 947,637 | 2,038,599
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 6,605 | 6,690
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 120 | 8,423
Available for sale securities, Unrealized Loss Position, Accumulated Loss | $ 6,725 | $ 15,113
Commercial agency mortgage-backed securities [Member] |  |
Available for sale, Unrealized Loss Position [Line Items] |  |
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | 37 | 69
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 350,506 | $ 830,047
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 277,627 | 210,877
Available for sale securities, Unrealized Loss Position, Fair Value | 628,133 | 1,040,924
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 1,587 | 4,238
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 494 | 907
Available for sale securities, Unrealized Loss Position, Accumulated Loss | $ 2,081 | $ 5,145
Other debt securities [Member] |  |
Available for sale, Unrealized Loss Position [Line Items] |  |
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions | 1 | 1
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 0 | $ 0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 472 | 472
Available for sale securities, Unrealized Loss Position, Fair Value | 472 | 472
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 28 | 28
Available for sale securities, Unrealized Loss Position, Accumulated Loss | $ 28 | $ 28

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- Definition Amount of allowance for credit 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 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 9 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922900-210455 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aaa) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121558606&loc=SL82898722-210454 + Details
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