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Securities - Available-for-sale Securities in Continuous Loss Position (Details) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2017 USD ($) investment | Dec. 31, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items] |  |
Less than 12 Months, Fair Value | $ 41,276 | $ 88,133
Less than 12 Months, Gross Unrealized Losses | (341) | (1,433)
12 Months or Greater, Fair Value | 25,990 | 8,948
12 Months or Greater, Gross Unrealized Losses | (539) | (400)
Total, Fair Value | 67,266 | 97,081
Total, Gross Unrealized Losses | (880) | (1,833)
U.S. Government-sponsored enterprises (GSEs) [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Less than 12 Months, Fair Value | 6,110 | 14,702
Less than 12 Months, Gross Unrealized Losses | (113) | (564)
12 Months or Greater, Fair Value | 7,804 | 0
12 Months or Greater, Gross Unrealized Losses | (196) | 0
Total, Fair Value | 13,914 | 14,702
Total, Gross Unrealized Losses | $ (309) | (564)
Number of investments in unrealized loss positions | investment | 5 |
Municipal securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Less than 12 Months, Fair Value | $ 1,839 | 6,368
Less than 12 Months, Gross Unrealized Losses | (18) | (179)
12 Months or Greater, Fair Value | 1,305 | 0
12 Months or Greater, Gross Unrealized Losses | (23) | 0
Total, Fair Value | 3,144 | 6,368
Total, Gross Unrealized Losses | $ (41) | (179)
Number of investments in unrealized loss positions | investment | 8 |
Other debt securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Less than 12 Months, Fair Value | $ 938 |
Less than 12 Months, Gross Unrealized Losses | (35) |
12 Months or Greater, Fair Value | 0 |
12 Months or Greater, Gross Unrealized Losses | 0 |
Total, Fair Value | 938 |
Total, Gross Unrealized Losses | $ (35) |
Number of investments in unrealized loss positions | investment | 1 |
Mortgage-backed securities [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Less than 12 Months, Fair Value | $ 32,389 | 67,063
Less than 12 Months, Gross Unrealized Losses | (175) | (690)
12 Months or Greater, Fair Value | 16,881 | 8,948
12 Months or Greater, Gross Unrealized Losses | (320) | (400)
Total, Fair Value | 49,270 | 76,011
Total, Gross Unrealized Losses | $ (495) | $ (1,090)
Number of investments in unrealized loss positions | investment | 40 |

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- Definition Amount of unrealized loss on securities classified as available-for-sale that have been in a loss position for twelve months or longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
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- Definition Amount of unrealized loss on securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
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- Definition Amount of unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
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