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Allowance for Loan Losses - Investments in Loans Considered to be Impaired and Related Information on Impaired Loans (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Financing Receivable, Impaired [Line Items] |  |  |  |  |
With a related allowance recorded, Recorded Investment | $ 520 |  | $ 520 |  | $ 1,783
With a related allowance recorded, Unpaid Principal Balance | 520 |  | 520 |  | 1,835
Impaired financing receivable, Related Allowance | 294 |  | 294 |  | 77
Without a related allowance recorded, Recorded Investment | 30,208 |  | 30,208 |  | 25,040
Without a related allowance, Unpaid Principal Balance | 34,811 |  | 34,811 |  | 31,302
Impaired Financing Receivable, Recorded Investment, Total | 30,728 |  | 30,728 |  | 26,823
Impaired Financing Receivable, Total Unpaid Principal Balance, Total | 35,331 |  | 35,331 |  | 33,137
With a related allowance recorded, Average Recorded Investment | 528 | $ 2,461 | 28,321 | $ 36,321 |
With a related allowance recorded, Interest Income Recognized | 1 | 40 | 862 | 881 |
Without a related allowance recorded, Average Recorded Investment | 30,298 | 33,806 | 622 | 1,277 |
Without a related allowance recorded, Interest Income Recognized | 287 | 639 | 2 | 46 |
Impaired financing receivable, Average Recorded Investment, Total | 30,826 | 36,267 | 28,943 | 37,598 |
Impaired financing Receivable, Interest Income Recognized, Total | 288 | 679 | 864 | 927 |
Commercial real estate |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
With a related allowance recorded, Recorded Investment | 0 |  | 0 |  | 0
With a related allowance recorded, Unpaid Principal Balance | 0 |  | 0 |  | 0
Impaired financing receivable, Related Allowance | 0 |  | 0 |  | 0
Without a related allowance recorded, Recorded Investment | 3,703 |  | 3,703 |  | 3,546
Without a related allowance, Unpaid Principal Balance | 4,069 |  | 4,069 |  | 3,811
Impaired Financing Receivable, Recorded Investment, Total | 3,703 |  | 3,703 |  | 3,546
Impaired Financing Receivable, Total Unpaid Principal Balance, Total | 4,069 |  | 4,069 |  | 3,811
With a related allowance recorded, Average Recorded Investment | 0 | 0 | 3,895 | 6,577 |
With a related allowance recorded, Interest Income Recognized | 0 | 0 | 126 | 140 |
Without a related allowance recorded, Average Recorded Investment | 3,744 | 6,415 | 0 | 0 |
Without a related allowance recorded, Interest Income Recognized | 41 | 105 | 0 | 0 |
Impaired financing receivable, Average Recorded Investment, Total | 3,744 | 6,415 | 3,895 | 6,577 |
Impaired financing Receivable, Interest Income Recognized, Total | 41 | 105 | 126 | 140 |
Commercial and industrial |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
With a related allowance recorded, Recorded Investment | 0 |  | 0 |  | 1,735
With a related allowance recorded, Unpaid Principal Balance | 0 |  | 0 |  | 1,787
Impaired financing receivable, Related Allowance | 0 |  | 0 |  | 29
Without a related allowance recorded, Recorded Investment | 14,548 |  | 14,548 |  | 5,549
Without a related allowance, Unpaid Principal Balance | 16,271 |  | 16,271 |  | 7,980
Impaired Financing Receivable, Recorded Investment, Total | 14,548 |  | 14,548 |  | 7,284
Impaired Financing Receivable, Total Unpaid Principal Balance, Total | 16,271 |  | 16,271 |  | 9,767
With a related allowance recorded, Average Recorded Investment | 0 | 2,406 | 11,567 | 11,001 |
With a related allowance recorded, Interest Income Recognized | 0 | 37 | 232 | 164 |
Without a related allowance recorded, Average Recorded Investment | 14,412 | 9,074 | 0 | 1,218 |
Without a related allowance recorded, Interest Income Recognized | 73 | 130 | 0 | 44 |
Impaired financing receivable, Average Recorded Investment, Total | 14,412 | 11,480 | 11,567 | 12,219 |
Impaired financing Receivable, Interest Income Recognized, Total | 73 | 167 | 232 | 208 |
Commercial construction |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
With a related allowance recorded, Recorded Investment | 490 |  | 490 |  | 0
With a related allowance recorded, Unpaid Principal Balance | 489 |  | 489 |  | 0
Impaired financing receivable, Related Allowance | 268 |  | 268 |  | 0
Without a related allowance recorded, Recorded Investment | 2,808 |  | 2,808 |  | 5,464
Without a related allowance, Unpaid Principal Balance | 4,318 |  | 4,318 |  | 8,132
Impaired Financing Receivable, Recorded Investment, Total | 3,298 |  | 3,298 |  | 5,464
Impaired Financing Receivable, Total Unpaid Principal Balance, Total | 4,807 |  | 4,807 |  | 8,132
With a related allowance recorded, Average Recorded Investment | 496 | 0 | 2,813 | 7,222 |
With a related allowance recorded, Interest Income Recognized | 0 | 0 | 134 | 194 |
Without a related allowance recorded, Average Recorded Investment | 2,809 | 7,140 | 585 | 0 |
Without a related allowance recorded, Interest Income Recognized | 61 | 154 | 0 | 0 |
Impaired financing receivable, Average Recorded Investment, Total | 3,305 | 7,140 | 3,398 | 7,222 |
Impaired financing Receivable, Interest Income Recognized, Total | 61 | 154 | 134 | 194 |
Consumer real estate |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
With a related allowance recorded, Recorded Investment | 15 |  | 15 |  | 21
With a related allowance recorded, Unpaid Principal Balance | 15 |  | 15 |  | 21
Impaired financing receivable, Related Allowance | 10 |  | 10 |  | 21
Without a related allowance recorded, Recorded Investment | 9,142 |  | 9,142 |  | 10,467
Without a related allowance, Unpaid Principal Balance | 10,138 |  | 10,138 |  | 11,357
Impaired Financing Receivable, Recorded Investment, Total | 9,157 |  | 9,157 |  | 10,488
Impaired Financing Receivable, Total Unpaid Principal Balance, Total | 10,153 |  | 10,153 |  | 11,378
With a related allowance recorded, Average Recorded Investment | 15 | 23 | 10,031 | 11,488 |
With a related allowance recorded, Interest Income Recognized | 0 | 1 | 370 | 382 |
Without a related allowance recorded, Average Recorded Investment | 9,320 | 11,149 | 16 | 24 |
Without a related allowance recorded, Interest Income Recognized | 112 | 250 | 1 | 1 |
Impaired financing receivable, Average Recorded Investment, Total | 9,335 | 11,172 | 10,047 | 11,512 |
Impaired financing Receivable, Interest Income Recognized, Total | 112 | 251 | 371 | 383 |
Other consumer |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
With a related allowance recorded, Recorded Investment | 15 |  | 15 |  | 27
With a related allowance recorded, Unpaid Principal Balance | 16 |  | 16 |  | 27
Impaired financing receivable, Related Allowance | 16 |  | 16 |  | 27
Without a related allowance recorded, Recorded Investment | 7 |  | 7 |  | 14
Without a related allowance, Unpaid Principal Balance | 15 |  | 15 |  | 22
Impaired Financing Receivable, Recorded Investment, Total | 22 |  | 22 |  | 41
Impaired Financing Receivable, Total Unpaid Principal Balance, Total | 31 |  | 31 |  | $ 49
With a related allowance recorded, Average Recorded Investment | 17 | 32 | 15 | 33 |
With a related allowance recorded, Interest Income Recognized | 1 | 2 | 0 | 1 |
Without a related allowance recorded, Average Recorded Investment | 13 | 28 | 21 | 35 |
Without a related allowance recorded, Interest Income Recognized | 0 | 0 | 1 | 1 |
Impaired financing receivable, Average Recorded Investment, Total | 30 | 60 | 36 | 68 |
Impaired financing Receivable, Interest Income Recognized, Total | $ 1 | $ 2 | $ 1 | $ 2 |

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