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Investments - Schedule of Available for Sale Securities Continuous Unrealized Loss Position Fair Value (Details) $ in Thousands | Sep. 30, 2018 USD ($) Number | Dec. 31, 2017 USD ($) Number
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
No. of securities | Number | 558 | 345
Fair value, Less than 12 months | $ 197,750 | $ 134,700
Unrealized losses, Less than 12 months | (4,100) | (1,022)
Fair value, 12 months or longer | 139,022 | 89,790
Unrealized losses, 12 months or longer | (5,929) | (2,001)
Total, Fair value | 336,772 | 224,490
Total, Unrealized losses | $ (10,029) | $ (3,023)
US Treasury Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
No. of securities | Number | 1 | 1
Fair value, Less than 12 months | $ 1,943 | $ 1,990
Unrealized losses, Less than 12 months | (56) | (9)
Fair value, 12 months or longer |  |
Unrealized losses, 12 months or longer |  |
Total, Fair value | 1,943 | 1,990
Total, Unrealized losses | $ (56) | $ (9)
US Federal Agency Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
No. of securities | Number | 11 | 14
Fair value, Less than 12 months | $ 5,135 | $ 7,989
Unrealized losses, Less than 12 months | (42) | (24)
Fair value, 12 months or longer | 9,733 | 8,272
Unrealized losses, 12 months or longer | (48) | (61)
Total, Fair value | 14,868 | 16,261
Total, Unrealized losses | $ (90) | $ (85)
Municipal Obligations, Tax Exempt [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
No. of securities | Number | 333 | 178
Fair value, Less than 12 months | $ 91,206 | $ 37,299
Unrealized losses, Less than 12 months | (1,981) | (273)
Fair value, 12 months or longer | 45,530 | 31,930
Unrealized losses, 12 months or longer | (2,384) | (807)
Total, Fair value | 136,736 | 69,229
Total, Unrealized losses | $ (4,365) | $ (1,080)
Municipal Obligations, Taxable [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
No. of securities | Number | 110 | 73
Fair value, Less than 12 months | $ 31,740 | $ 18,792
Unrealized losses, Less than 12 months | (553) | (96)
Fair value, 12 months or longer | 15,644 | 9,744
Unrealized losses, 12 months or longer | (371) | (120)
Total, Fair value | 47,384 | 28,536
Total, Unrealized losses | $ (924) | $ (216)
Agency Mortgage-backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
No. of securities | Number | 103 | 79
Fair value, Less than 12 months | $ 67,726 | $ 68,630
Unrealized losses, Less than 12 months | (1,468) | (620)
Fair value, 12 months or longer | 68,115 | 39,844
Unrealized losses, 12 months or longer | (3,126) | (1,013)
Total, Fair value | 135,841 | 108,474
Total, Unrealized losses | $ (4,594) | $ (1,633)

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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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 Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. + References No definition available. + Details
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- Definition Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
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