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Securities Available-for-Sale - Additional Information (Details) | Dec. 31, 2016 USD ($) security | Dec. 31, 2015 USD ($)
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Schedule of Available-for-sale Securities [Line Items] |  |
Number of debt securities on which unrealized losses were primarily attributable to changes in interest | security | 31 |
Unrealized losses on marketable securities | $ 3,472,000 | $ 1,716,000
Carrying values of securities | 342,000,000 | 278,400,000
Marketable equity securities |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Unrealized losses on marketable securities | $ 0 | $ 0

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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://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=73527792&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)(2) -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 + Details
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- Definition The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for FHLB debt obligations, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729 + Details
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