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Investment Securities Held to Maturity Securities by Type (Details) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
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Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-maturity | $ 384,909 | $ 393,855
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 752 | 387
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (5,218) | (10,249)
Securities held to maturity, fair value | 380,443 | 383,993
US Government Agencies Residential Mortgage-backed Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-maturity | 3,606 | 3,635
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (26) | (97)
Securities held to maturity, fair value | 3,580 | 3,538
US Government Agency Debt Securities Commercial [Domain] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-maturity | 54,898 | 55,221
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (1,763) | (2,327)
Securities held to maturity, fair value | 53,135 | 52,894
Residential Mortgage Backed Securities [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-maturity | 270,807 | 279,109
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 352 | 212
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (3,303) | (7,254)
Securities held to maturity, fair value | 267,856 | 272,067
Obligations of U.S. Government-Sponsored Enterprises - Mortgage-Backed Securities - Commercial [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-maturity | 12,894 | 13,159
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (95) | (258)
Securities held to maturity, fair value | 12,799 | 12,901
Obligations of States and Political Subdivisions [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-maturity | 42,304 | 42,331
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 400 | 175
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | (31) | (313)
Securities held to maturity, fair value | 42,673 | 42,193
Debt Security, Government, Non-US [Member] |  |
Schedule of Held-to-maturity Securities [Line Items] |  |
Debt Securities, Held-to-maturity | 400 | 400
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 0 | 0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | 0 | 0
Securities held to maturity, fair value | $ 400 | $ 400

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- Definition Amount of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563 + Details
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- Definition Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563 + Details
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- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563 + Details
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