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Employee Benefits - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract] |  |
Prior service credit | $ 0 | $ (1,029)
Net actuarial loss | 26,013 | 34,376
Total (Before Tax Effects) | $ 26,013 | $ 33,347

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- Definition Amount before tax, after reclassification adjustments, of actuarial gain (loss) that has not been recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669646-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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