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Other Real Estate Owned (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Real Estate Acquired Through Foreclosure [Roll Forward] |  |  |
Balance at beginning of year | $ 10,019 | $ 6,300 | $ 13,600
Acquisitions | 1,200 | 1,100 | 0
Additions | 5,400 | 7,600 | 5,600
Valuation adjustments | (400) | (600) | (200)
Dispositions | (6,100) | (4,400) | (12,700)
Balance at end of year | 10,053 | 10,019 | 6,300
Write-downs of OREO | 400 | 600 | 200
Write-down due to change in appraised value | 300 | 550 | 100
Write-down due to change in management estimates | $ 100 | $ 50 | $ 100

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- Definition The charge against earnings in the period to reduce the carrying amount of real property to fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2921-110230 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
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