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Investment Securities - Other Than Temporarily Impaired Debt Securities (Details) $ in Thousands | Dec. 31, 2018 USD ($) security | Dec. 31, 2017 USD ($) security
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Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items] |  |
Number of investment securities in unrealized loss positions | security | 229 | 198
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] |  |
Held-to-maturity, Less than 12 continuous months, Fair value | $ 3,078 | $ 31,051
Held-to-maturity, Less than 12 continuous months, Unrealized loss | (12) | (205)
Held-to-maturity, Greater than 12 continuous months, Fair value | 127,053 | 60,669
Held-to-maturity, Greater than 12 continuous months, Unrealized loss | (3,510) | (414)
Held-to-maturity, Total securities in a loss position, Fair value | 130,131 | 91,720
Held-to-maturity, Total securities in a loss position, Unrealized loss | (3,522) | (619)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 81,533 | 212,675
Available-for-sale, Less than 12 continuous months, Unrealized loss | (657) | (1,465)
Available-for-sale, Greater than 12 continuous months, Fair value | 234,850 | 40,478
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (4,537) | (927)
Available-for-sale, Unrealized loss position, Fair value | 316,383 | 253,153
Available-for-sale, Total securities in a loss position, Unrealized loss | (5,194) | (2,392)
Available-for-sale and Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract] [Abstract] |  |
Total temporarily impaired securities, Less than 12 continuous months, Fair value | 84,611 | 243,726
Total temporarily impaired securities, Less than 12 continuous months, Unrealized loss | (669) | (1,670)
Total temporarily impaired securities, Greater than 12 continuous months, Fair value | 361,903 | 101,147
Total temporarily impaired securities, Greater than 12 continuous months, Unrealized loss | (8,047) | (1,341)
Total temporarily impaired securities, Total securities in a loss position, Fair value | 446,514 | 344,873
Total temporarily impaired securities, Total securities in a loss position, Unrealized loss | $ (8,716) | (3,011)
Number of securities in continuous loss position for more than 12 months | security | 188 |
Number of securities in continuous loss position for less than 12 months | security | 41 |
MBS pass-through securities issued by FHLMC and FNMA |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] |  |
Held-to-maturity, Less than 12 continuous months, Fair value | $ 198 | 16,337
Held-to-maturity, Less than 12 continuous months, Unrealized loss | (9) | (143)
Held-to-maturity, Greater than 12 continuous months, Fair value | 83,990 | 46,845
Held-to-maturity, Greater than 12 continuous months, Unrealized loss | (2,800) | (371)
Held-to-maturity, Total securities in a loss position, Fair value | 84,188 | 63,182
Held-to-maturity, Total securities in a loss position, Unrealized loss | (2,809) | (514)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 19,971 | 32,189
Available-for-sale, Less than 12 continuous months, Unrealized loss | (128) | (121)
Available-for-sale, Greater than 12 continuous months, Fair value | 50,077 | 15,325
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (1,102) | (302)
Available-for-sale, Unrealized loss position, Fair value | 70,048 | 47,514
Available-for-sale, Total securities in a loss position, Unrealized loss | (1,230) | (423)
CMOs issued by FNMA |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] |  |
Held-to-maturity, Less than 12 continuous months, Fair value | 0 |
Held-to-maturity, Less than 12 continuous months, Unrealized loss | 0 |
Held-to-maturity, Greater than 12 continuous months, Fair value | 11,327 |
Held-to-maturity, Greater than 12 continuous months, Unrealized loss | (120) |
Held-to-maturity, Total securities in a loss position, Fair value | 11,327 |
Held-to-maturity, Total securities in a loss position, Unrealized loss | (120) | 0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 2,345 | 26,401
Available-for-sale, Less than 12 continuous months, Unrealized loss | (8) | (171)
Available-for-sale, Greater than 12 continuous months, Fair value | 16,138 | 5,440
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (322) | (77)
Available-for-sale, Unrealized loss position, Fair value | 18,483 | 31,841
Available-for-sale, Total securities in a loss position, Unrealized loss | (330) | (248)
Obligations of state and political subdivisions |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] |  |
Held-to-maturity, Less than 12 continuous months, Fair value | 0 | 3,648
Held-to-maturity, Less than 12 continuous months, Unrealized loss | 0 | (31)
Held-to-maturity, Greater than 12 continuous months, Fair value | 3,565 | 0
Held-to-maturity, Greater than 12 continuous months, Unrealized loss | (23) | 0
Held-to-maturity, Total securities in a loss position, Fair value | 3,565 | 3,648
Held-to-maturity, Total securities in a loss position, Unrealized loss | (23) | (31)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 15,290 | 52,197
Available-for-sale, Less than 12 continuous months, Unrealized loss | (54) | (288)
Available-for-sale, Greater than 12 continuous months, Fair value | 52,804 | 19,548
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (1,166) | (546)
Available-for-sale, Unrealized loss position, Fair value | 68,094 | 71,745
Available-for-sale, Total securities in a loss position, Unrealized loss | (1,220) | (834)
CMOs issued by FHLMC |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] |  |
Held-to-maturity, Less than 12 continuous months, Fair value | 2,880 | 11,066
Held-to-maturity, Less than 12 continuous months, Unrealized loss | (3) | (31)
Held-to-maturity, Greater than 12 continuous months, Fair value | 28,171 | 13,824
Held-to-maturity, Greater than 12 continuous months, Unrealized loss | (567) | (43)
Held-to-maturity, Total securities in a loss position, Fair value | 31,051 | 24,890
Held-to-maturity, Total securities in a loss position, Unrealized loss | (570) | (74)
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 24,094 | 69,276
Available-for-sale, Less than 12 continuous months, Unrealized loss | (330) | (628)
Available-for-sale, Greater than 12 continuous months, Fair value | 74,243 | 0
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (1,267) | 0
Available-for-sale, Unrealized loss position, Fair value | 98,337 | 69,276
Available-for-sale, Total securities in a loss position, Unrealized loss | (1,597) | (628)
CMOs issued by GNMA |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] |  |
Held-to-maturity, Total securities in a loss position, Unrealized loss | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 1,666 | 14,230
Available-for-sale, Less than 12 continuous months, Unrealized loss | (7) | (194)
Available-for-sale, Greater than 12 continuous months, Fair value | 9,112 | 0
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (267) | 0
Available-for-sale, Unrealized loss position, Fair value | 10,778 | 14,230
Available-for-sale, Total securities in a loss position, Unrealized loss | (274) | (194)
Corporate bonds |  |
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 0 | 3,060
Available-for-sale, Less than 12 continuous months, Unrealized loss | 0 | (3)
Available-for-sale, Greater than 12 continuous months, Fair value | 1,004 |
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (14) |
Available-for-sale, Unrealized loss position, Fair value | 1,004 | 3,060
Available-for-sale, Total securities in a loss position, Unrealized loss | (14) | (3)
SBA-backed securities |  |
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract] |  |
Held-to-maturity, Total securities in a loss position, Unrealized loss | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 13,175 | 11,028
Available-for-sale, Less than 12 continuous months, Unrealized loss | (122) | (53)
Available-for-sale, Greater than 12 continuous months, Fair value | 20,123 | 165
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (284) | (2)
Available-for-sale, Unrealized loss position, Fair value | 33,298 | 11,193
Available-for-sale, Total securities in a loss position, Unrealized loss | (406) | (55)
Debentures of government- sponsored agencies |  |
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value | 4,992 | 2,984
Available-for-sale, Less than 12 continuous months, Unrealized loss | (8) | (5)
Available-for-sale, Greater than 12 continuous months, Fair value | 11,349 | 0
Available-for-sale, Greater than 12 continuous months, Unrealized loss | (115) | 0
Available-for-sale, Unrealized loss position, Fair value | 16,341 | 2,984
Available-for-sale, Total securities in a loss position, Unrealized loss | (123) | (5)
Privately issued CMOs |  |
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |  |
Available-for-sale, Less than 12 continuous months, Fair value |  | 1,310
Available-for-sale, Less than 12 continuous months, Unrealized loss |  | (2)
Available-for-sale, Greater than 12 continuous months, Fair value |  | 0
Available-for-sale, Greater than 12 continuous months, Unrealized loss |  | 0
Available-for-sale, Unrealized loss position, Fair value | 0 | 1,310
Available-for-sale, Total securities in a loss position, Unrealized loss | $ 0 | $ (2)

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