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Securities - Summary of Gross Unrealized Losses and Fair Values, Aggregated by Investment Category and Length of Individual Securities Continuous Unrealized Loss Position Available-for-sale (Details) $ in Thousands | Sep. 30, 2021 USD ($) Security | Dec. 31, 2020 USD ($) Security
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Schedule Of Available For Sale Securities [Line Items] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security | 97 | 37
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 822,458 | $ 170,971
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses | (17,405) | (1,016)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 48,269 | 5,424
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses | (1,496) | (33)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 870,727 | 176,395
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses | $ (18,901) | $ (1,049)
U.S. Government Agencies |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security | 10 | 5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 74,687 | $ 30,639
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses | (1,506) | (137)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 9,641 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses | (359) | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 84,328 | 30,639
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses | $ (1,865) | $ (137)
Obligations of States, Municipalities, and Political Subdivisions |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security | 7 | 2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 8,097 | $ 210
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses | (164) | (85)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 8,097 | 210
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses | $ (164) | $ (85)
Agency, Residential Mortgage-Backed Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security | 51 | 8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 620,325 | $ 45,253
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses | (12,626) | (198)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 11,805 | 472
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses | (360) | (7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 632,130 | 45,725
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses | $ (12,986) | $ (205)
Non-Agency, Residential Mortgage-Backed Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security | 5 | 2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 34,310 | $ 3,963
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses | (722) | (5)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 34,310 | 3,963
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses | $ (722) | $ (5)
Agency, Commercial Mortgage-Backed Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security | 21 | 8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 75,001 | $ 55,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses | (2,369) | (390)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 26,823 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses | (777) | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 101,824 | 55,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses | $ (3,146) | $ (390)
Corporate Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security | 2 | 6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 5,041 | $ 10,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses | (17) | (102)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 5,041 | 10,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses | $ (17) | $ (102)
Asset-Backed Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security | 1 | 6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value | $ 4,997 | $ 24,436
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses | (1) | (99)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | 0 | 4,952
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses | 0 | (26)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 4,997 | 29,388
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses | $ (1) | $ (125)

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- Definition Amount of accumulated unrealized loss on investment in debt security 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 allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922890-210455 + Details
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