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Income Taxes - Significant Components of Temporary Differences with Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands | Dec. 31, 2016 | Dec. 31, 2015
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Deferred Tax Liabilities: |  |
Net unrealized holding gains on securities available-for-sale | $ (2,557) | $ (3,563)
Prepaid pension | (2,770) | (2,865)
Deferred loan income | (3,815) | (2,847)
Depreciation on premises and equipment | (1,239) | (1,226)
Other | (1,766) | (809)
Total Deferred Tax liabilities | (12,147) | (11,310)
Deferred Tax Assets: |  |
Allowance for loan losses | 19,446 | 17,740
Purchase accounting adjustments | 365 | 1,298
Other employee benefits | 3,983 | 2,556
Low income housing partnerships | 4,845 | 4,531
Net adjustment to funded status of pension | 10,018 | 12,425
Impairment of securities | 1,318 | 1,354
State net operating loss carryforwards | 3,114 | 2,670
Other | 4,984 | 6,155
Gross Deferred Tax Assets | 48,073 | 48,729
Less: Valuation allowance | (3,114) | (2,670)
Total Deferred Tax Assets | 44,959 | 46,059
Net Deferred Tax Asset | $ 32,812 | $ 34,749

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