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Investments - Schedule of Available-for-sale Securities (Details) - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | $ 362,462 | $ 393,631
Gross unrealized gains | 7,243 | 829
Gross unrealized losses | (388) | (6,115)
Estimated fair value | 369,317 | 388,345
U.S. Treasury Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 2,298 | 1,999
Gross unrealized gains | 16 |
Gross unrealized losses |  | (28)
Estimated fair value | 2,314 | 1,971
U.S. Federal Agency Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 4,015 | 10,370
Gross unrealized gains | 98 | 32
Gross unrealized losses |  | (41)
Estimated fair value | 4,113 | 10,361
Municipal Obligations, Tax Exempt [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 149,193 | 161,529
Gross unrealized gains | 3,565 | 353
Gross unrealized losses | (80) | (2,770)
Estimated fair value | 152,678 | 159,112
Municipal Obligations, Taxable [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 47,479 | 53,178
Gross unrealized gains | 1,620 | 180
Gross unrealized losses | (2) | (323)
Estimated fair value | 49,097 | 53,035
Agency Mortgage-backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 156,134 | 158,765
Gross unrealized gains | 1,944 | 264
Gross unrealized losses | (306) | (2,953)
Estimated fair value | 157,772 | 156,076
Certificates of Deposit [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized cost | 3,343 | 7,790
Gross unrealized gains |  |
Gross unrealized losses |  |
Estimated fair value | $ 3,343 | $ 7,790

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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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- Definition Amount, before tax, of unrealized loss 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 (c) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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