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Investment Securities - Unrealized Loss Positions (Details) - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018
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Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 continuous months | $ 9,063 | $ 3,078
Greater than or equal to 12 continuous months | 25,665 | 127,053
Total Securities in a loss position | 34,728 | 130,131
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Less than 12 continuous months | (24) | (12)
Greater than or equal to 12 continuous months | (201) | (3,510)
Held-to-maturity, Gross Unrealized Losses | (225) | (3,522)
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 15,019 | 81,533
Available-for-sale, greater than 12 continuous months, Fair value | 21,735 | 234,850
Available-for-sale, Total Securities in a loss position, Fair Value | 36,754 | 316,383
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | (64) | (657)
Available-for-sale, greater than 12 continuous months, Unrealized loss | (138) | (4,537)
Available-for-sale, Total Securities in a loss position, Unrealized loss | (202) | (5,194)
Marketable Securities, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Marketable securities, less than 12 continuous months, Fair value | 24,082 | 84,611
Marketable securities, greater than 12 continuous months, Fair value | 47,400 | 361,903
Marketable securities, Total Securities in a loss position, Fair value | 71,482 | 446,514
Marketable Securities, Continuous Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Marketable securities, less than 12 continuous months, Unrealized loss | (88) | (669)
Marketable securities, greater than 12 continuous months, Unrealized loss | (339) | (8,047)
Marketable securities, Total Securities in a loss position, Unrealized loss | (427) | (8,716)
MBS pass-through securities issued by FHLMC and FNMA |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 continuous months | 9,063 | 198
Greater than or equal to 12 continuous months | 23,799 | 83,990
Total Securities in a loss position | 32,862 | 84,188
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Less than 12 continuous months | (24) | (9)
Greater than or equal to 12 continuous months | (191) | (2,800)
Held-to-maturity, Gross Unrealized Losses | (215) | (2,809)
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 269 | 19,971
Available-for-sale, greater than 12 continuous months, Fair value | 7,628 | 50,077
Available-for-sale, Total Securities in a loss position, Fair Value | 7,897 | 70,048
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | (1) | (128)
Available-for-sale, greater than 12 continuous months, Unrealized loss | (46) | (1,102)
Available-for-sale, Total Securities in a loss position, Unrealized loss | (47) | (1,230)
SBA-backed securities |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 0 | 13,175
Available-for-sale, greater than 12 continuous months, Fair value | 2,785 | 20,123
Available-for-sale, Total Securities in a loss position, Fair Value | 2,785 | 33,298
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | 0 | (122)
Available-for-sale, greater than 12 continuous months, Unrealized loss | (61) | (284)
Available-for-sale, Total Securities in a loss position, Unrealized loss | (61) | (406)
CMOs issued by FNMA |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 continuous months |  | 0
Greater than or equal to 12 continuous months |  | 11,327
Total Securities in a loss position |  | 11,327
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Less than 12 continuous months |  | 0
Greater than or equal to 12 continuous months |  | (120)
Held-to-maturity, Gross Unrealized Losses |  | (120)
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 0 | 2,345
Available-for-sale, greater than 12 continuous months, Fair value | 0 | 16,138
Available-for-sale, Total Securities in a loss position, Fair Value | 0 | 18,483
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | 0 | (8)
Available-for-sale, greater than 12 continuous months, Unrealized loss | 0 | (322)
Available-for-sale, Total Securities in a loss position, Unrealized loss | 0 | (330)
CMOs issued by FHLMC |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 continuous months | 0 | 2,880
Greater than or equal to 12 continuous months | 1,866 | 28,171
Total Securities in a loss position | 1,866 | 31,051
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Less than 12 continuous months | 0 | (3)
Greater than or equal to 12 continuous months | (10) | (567)
Held-to-maturity, Gross Unrealized Losses | (10) | (570)
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 7,735 | 24,094
Available-for-sale, greater than 12 continuous months, Fair value | 9,722 | 74,243
Available-for-sale, Total Securities in a loss position, Fair Value | 17,457 | 98,337
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | (13) | (330)
Available-for-sale, greater than 12 continuous months, Unrealized loss | (25) | (1,267)
Available-for-sale, Total Securities in a loss position, Unrealized loss | (38) | (1,597)
CMOs issued by GNMA |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 0 | 1,666
Available-for-sale, greater than 12 continuous months, Fair value | 130 | 9,112
Available-for-sale, Total Securities in a loss position, Fair Value | 130 | 10,778
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | 0 | (7)
Available-for-sale, greater than 12 continuous months, Unrealized loss | (1) | (267)
Available-for-sale, Total Securities in a loss position, Unrealized loss | (1) | (274)
Debentures of government- sponsored agencies |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value |  | 4,992
Available-for-sale, greater than 12 continuous months, Fair value |  | 11,349
Available-for-sale, Total Securities in a loss position, Fair Value |  | 16,341
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss |  | (8)
Available-for-sale, greater than 12 continuous months, Unrealized loss |  | (115)
Available-for-sale, Total Securities in a loss position, Unrealized loss |  | (123)
Privately issued CMOs |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 79 |
Available-for-sale, greater than 12 continuous months, Fair value | 0 |
Available-for-sale, Total Securities in a loss position, Fair Value | 79 |
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | (1) |
Available-for-sale, greater than 12 continuous months, Unrealized loss | 0 |
Available-for-sale, Total Securities in a loss position, Unrealized loss | (1) |
Obligations of state and political subdivisions |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 continuous months |  | 0
Greater than or equal to 12 continuous months |  | 3,565
Total Securities in a loss position |  | 3,565
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Less than 12 continuous months |  | 0
Greater than or equal to 12 continuous months |  | (23)
Held-to-maturity, Gross Unrealized Losses |  | (23)
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 6,936 | 15,290
Available-for-sale, greater than 12 continuous months, Fair value | 966 | 52,804
Available-for-sale, Total Securities in a loss position, Fair Value | 7,902 | 68,094
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | (49) | (54)
Available-for-sale, greater than 12 continuous months, Unrealized loss | (4) | (1,166)
Available-for-sale, Total Securities in a loss position, Unrealized loss | (53) | (1,220)
Corporate bonds |  |
Debt Securities, Available-For-Sale, Continuous Unrealized Loss Position, Fair Value [Abstract] |  |
Available-for-sale, less than 12 continuous months, Fair value | 0 | 0
Available-for-sale, greater than 12 continuous months, Fair value | 504 | 1,004
Available-for-sale, Total Securities in a loss position, Fair Value | 504 | 1,004
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] |  |
Available-for-sale, less than 12 continuous months, Unrealized loss | 0 | 0
Available-for-sale, greater than 12 continuous months, Unrealized loss | (1) | (14)
Available-for-sale, Total Securities in a loss position, Unrealized loss | $ (1) | $ (14)

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- Definition Amount of 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 more than 12 months, 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 326 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922890-210455 Reference 2: 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=118939692&loc=d3e27337-111563 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=118942371&loc=SL82922954-210456 + Details
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