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Securities, Available for Sale (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2020 | Mar. 31, 2019 | Dec. 31, 2019
Debt securities, available-for-sale [Abstract] |  |  |
Amortized cost | $ 972,858 |  | $ 968,554
Unrealized gains | 28,340 |  | 8,319
Unrealized losses | 218 |  | 1,533
Estimated fair value | 1,000,980 |  | 975,340
Allowance for credit losses on AFS securities | 0 |  |
Sales transactions of securities available for sale [Abstract] |  |  |
Gross realized gains | 3 | $ 53 |
Gross realized (losses) | 0 | (152) |
Net AFS realized gains (losses) | 3 | (99) |
Gains from calls on securities available for sale | 3 | $ 4 |
Federal Agency [Member] |  |  |
Debt securities, available-for-sale [Abstract] |  |  |
Amortized cost |  |  | 34,998
Unrealized gains |  |  | 3
Unrealized losses |  |  | 243
Estimated fair value |  |  | 34,758
State & Municipal [Member] |  |  |
Debt securities, available-for-sale [Abstract] |  |  |
Amortized cost | 2,533 |  | 2,533
Unrealized gains | 86 |  | 0
Unrealized losses | 0 |  | 20
Estimated fair value | 2,619 |  | 2,513
Mortgage-Backed, Government Sponsored Enterprises [Member] |  |  |
Debt securities, available-for-sale [Abstract] |  |  |
Amortized cost | 465,033 |  | 453,614
Unrealized gains | 15,787 |  | 4,982
Unrealized losses | 0 |  | 239
Estimated fair value | 480,820 |  | 458,357
Mortgage-Backed, U.S. Government Agency Securities [Member] |  |  |
Debt securities, available-for-sale [Abstract] |  |  |
Amortized cost | 50,109 |  | 44,758
Unrealized gains | 1,249 |  | 667
Unrealized losses | 55 |  | 156
Estimated fair value | 51,303 |  | 45,269
Collateralized Mortgage Obligations, Government-Sponsored Enterprises [Member] |  |  |
Debt securities, available-for-sale [Abstract] |  |  |
Amortized cost | 308,833 |  | 328,499
Unrealized gains | 9,221 |  | 1,949
Unrealized losses | 95 |  | 467
Estimated fair value | 317,959 |  | 329,981
Collateralized Mortgage Obligations, U.S. Government Agency Securities [Member] |  |  |
Debt securities, available-for-sale [Abstract] |  |  |
Amortized cost | 146,350 |  | 104,152
Unrealized gains | 1,997 |  | 718
Unrealized losses | 68 |  | 408
Estimated fair value | $ 148,279 |  | $ 104,462

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) 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 (b) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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