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Investment Securities, HTM Credit Quality Indicators (Details) - USD ($) $ in Thousands | Mar. 31, 2022 | Dec. 31, 2021
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Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | $ 3,939,920 | $ 2,239,003
Not Rated [Domain] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 895 | 896
US Treasury Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 998 | 1,000
US Treasury Securities | Not Rated [Domain] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
US States and Political Subdivisions Debt Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 1,696,536 | 1,628,759
US States and Political Subdivisions Debt Securities [Member] | Not Rated [Domain] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 895 | 896
FNMA/FHLMC | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 956,470 | 34,347
FNMA/FHLMC | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 764,775 | 425,937
FNMA/FHLMC | Not Rated [Domain] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
FNMA/FHLMC | Not Rated [Domain] | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
Government National Mortgage Association (GNMA) [Member] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 44,742 | 48,053
Government National Mortgage Association (GNMA) [Member] | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 92,383 | 100,907
Government National Mortgage Association (GNMA) [Member] | Not Rated [Domain] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
Government National Mortgage Association (GNMA) [Member] | Not Rated [Domain] | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
Mortgage-backed Securities, Issued by Private Enterprises [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 384,016 |
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 384,016 |
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Not Rated [Domain] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 |
AAA |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 3,005,450 | 1,312,642
AAA | US Treasury Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 998 | 1,000
AAA | US States and Political Subdivisions Debt Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 762,066 | 702,399
AAA | FNMA/FHLMC | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 956,470 | 34,347
AAA | FNMA/FHLMC | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 764,775 | 425,937
AAA | Government National Mortgage Association (GNMA) [Member] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 44,742 | 48,053
AAA | Government National Mortgage Association (GNMA) [Member] | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 92,383 | 100,907
AAA | Mortgage-backed Securities, Issued by Private Enterprises [Member] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 384,016 |
AA |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 920,883 | 914,591
AA | US Treasury Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
AA | US States and Political Subdivisions Debt Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 920,883 | 914,591
AA | FNMA/FHLMC | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
AA | FNMA/FHLMC | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
AA | Government National Mortgage Association (GNMA) [Member] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
AA | Government National Mortgage Association (GNMA) [Member] | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
AA | Mortgage-backed Securities, Issued by Private Enterprises [Member] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 |
A |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 12,692 | 10,873
A | US Treasury Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
A | US States and Political Subdivisions Debt Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 12,692 | 10,873
A | FNMA/FHLMC | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
A | FNMA/FHLMC | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
A | Government National Mortgage Association (GNMA) [Member] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | 0
A | Government National Mortgage Association (GNMA) [Member] | Commercial mortgage-related securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | 0 | $ 0
A | Mortgage-backed Securities, Issued by Private Enterprises [Member] | Residential Related Securities |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | $ 0 |

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