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Interest Rate Swaps (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Derivative [Line Items] |  |  |
Weighted average pay rate on interest-rate swaps | 4.46% | 4.34% | 4.25%
Weighted average receive rate on interest-rate swaps | 3.81% | 3.04% | 2.70%
Weighted average maturity (years) | 3 years 2 months 12 days | 4 years 9 months 18 days | 4 years 1 month 6 days
Fair value of interest-rate swaps | $ (653) | $ (685) | $ (789)
Loan yield maintenance provisions | 653 | 685 | 789
Interest rate swaps |  |  |
Derivative [Line Items] |  |  |
Notional amounts | $ 38,481 | $ 34,360 | $ 30,763

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