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Allowance for Loan Losses - Investments in Loans Considered to be Impaired and Related Information on Impaired Loans (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015 | Dec. 31, 2015
Financing Receivable, Impaired [Line Items] |  |  |  |  |
Without a related allowance recorded, Recorded Investment | $ 35,597 |  | $ 35,597 |  | $ 45,032
Without a related allowance, Unpaid Principal Balance | 41,565 |  | 41,565 |  | 50,286
Without a related allowance recorded, Related Allowance | 0 |  | 0 |  | 0
With a related allowance recorded, Recorded Investment | 2,462 |  | 2,462 |  | 618
With a related allowance recorded, Unpaid Principal Balance | 2,462 |  | 2,462 |  | 1,468
Impaired Financing Receivable, Recorded Investment | 38,059 |  | 38,059 |  | 45,650
Impaired Financing Receivable, Unpaid Principal Balance, Total | 44,027 |  | 44,027 |  | 51,754
Impaired Financing Receivable, Related Allowance | 2,235 |  | 2,235 |  | 37
Without a related allowance recorded, Average Recorded Investment | 34,665 | $ 41,140 | 35,365 | $ 40,631 |
Without a related allowance recorded, Interest Income Recognized | 298 | 555 | 806 | 1,342 |
With a related allowance recorded, Average Recorded Investment | 2,467 | 2,098 | 2,523 | 2,103 |
With a related allowance recorded, Interest Income Recognized | 37 | 9 | 102 | 47 |
Impaired Financing Receivable, Average Recorded Investment, Total | 37,132 | 43,238 | 37,888 | 42,734 |
Impaired Financing Receivable, Interest Income Recognized, Total | 335 | 564 | 908 | 1,389 |
Commercial and Industrial |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
Without a related allowance recorded, Recorded Investment | 8,261 |  | 8,261 |  | 14,417
Without a related allowance, Unpaid Principal Balance | 9,730 |  | 9,730 |  | 15,220
Without a related allowance recorded, Related Allowance | 0 |  | 0 |  | 0
With a related allowance recorded, Recorded Investment | 2,433 |  | 2,433 |  | 0
With a related allowance recorded, Unpaid Principal Balance | 2,433 |  | 2,433 |  | 0
Impaired Financing Receivable, Recorded Investment | 10,694 |  | 10,694 |  | 14,417
Impaired Financing Receivable, Unpaid Principal Balance, Total | 12,163 |  | 12,163 |  | 15,220
Impaired Financing Receivable, Related Allowance | 2,206 |  | 2,206 |  | 0
Without a related allowance recorded, Average Recorded Investment | 7,326 | 8,993 | 7,447 | 9,742 |
Without a related allowance recorded, Interest Income Recognized | 52 | 44 | 156 | 131 |
With a related allowance recorded, Average Recorded Investment | 2,437 | 1,977 | 2,492 | 1,980 |
With a related allowance recorded, Interest Income Recognized | 37 | 7 | 100 | 42 |
Impaired Financing Receivable, Average Recorded Investment, Total | 9,763 | 10,970 | 9,939 | 11,722 |
Impaired Financing Receivable, Interest Income Recognized, Total | 89 | 51 | 256 | 173 |
Commercial Real Estate |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
Without a related allowance recorded, Recorded Investment | 7,589 |  | 7,589 |  | 12,661
Without a related allowance, Unpaid Principal Balance | 7,818 |  | 7,818 |  | 13,157
Without a related allowance recorded, Related Allowance | 0 |  | 0 |  | 0
With a related allowance recorded, Recorded Investment | 0 |  | 0 |  | 0
With a related allowance recorded, Unpaid Principal Balance | 0 |  | 0 |  | 0
Impaired Financing Receivable, Recorded Investment | 7,589 |  | 7,589 |  | 12,661
Impaired Financing Receivable, Unpaid Principal Balance, Total | 7,818 |  | 7,818 |  | 13,157
Impaired Financing Receivable, Related Allowance | 0 |  | 0 |  | 0
Without a related allowance recorded, Average Recorded Investment | 7,582 | 14,101 | 7,551 | 14,994 |
Without a related allowance recorded, Interest Income Recognized | 38 | 352 | 106 | 731 |
With a related allowance recorded, Average Recorded Investment | 0 | 0 | 0 | 0 |
With a related allowance recorded, Interest Income Recognized | 0 | 0 | 0 | 0 |
Impaired Financing Receivable, Average Recorded Investment, Total | 7,582 | 14,101 | 7,551 | 14,994 |
Impaired Financing Receivable, Interest Income Recognized, Total | 38 | 352 | 106 | 731 |
Commercial Construction |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
Without a related allowance recorded, Recorded Investment | 7,987 |  | 7,987 |  | 10,998
Without a related allowance, Unpaid Principal Balance | 11,547 |  | 11,547 |  | 14,200
Without a related allowance recorded, Related Allowance | 0 |  | 0 |  | 0
With a related allowance recorded, Recorded Investment | 0 |  | 0 |  | 500
With a related allowance recorded, Unpaid Principal Balance | 0 |  | 0 |  | 1,350
Impaired Financing Receivable, Recorded Investment | 7,987 |  | 7,987 |  | 11,498
Impaired Financing Receivable, Unpaid Principal Balance, Total | 11,547 |  | 11,547 |  | 15,550
Impaired Financing Receivable, Related Allowance | 0 |  | 0 |  | 3
Without a related allowance recorded, Average Recorded Investment | 8,039 | 11,034 | 8,498 | 8,920 |
Without a related allowance recorded, Interest Income Recognized | 49 | 67 | 143 | 200 |
With a related allowance recorded, Average Recorded Investment | 0 | 0 |  | 0 |
With a related allowance recorded, Interest Income Recognized | 0 | 0 |  | 0 |
Impaired Financing Receivable, Average Recorded Investment, Total | 8,039 | 11,034 | 8,498 | 8,920 |
Impaired Financing Receivable, Interest Income Recognized, Total | 49 | 67 | 143 | 200 |
Consumer Real Estate |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
Without a related allowance recorded, Recorded Investment | 11,731 |  | 11,731 |  | 6,845
Without a related allowance, Unpaid Principal Balance | 12,434 |  | 12,434 |  | 7,521
Without a related allowance recorded, Related Allowance | 0 |  | 0 |  | 0
With a related allowance recorded, Recorded Investment | 27 |  | 27 |  | 116
With a related allowance recorded, Unpaid Principal Balance | 27 |  | 27 |  | 116
Impaired Financing Receivable, Recorded Investment | 11,758 |  | 11,758 |  | 6,961
Impaired Financing Receivable, Unpaid Principal Balance, Total | 12,461 |  | 12,461 |  | 7,637
Impaired Financing Receivable, Related Allowance | 27 |  | 27 |  | 32
Without a related allowance recorded, Average Recorded Investment | 11,686 | 6,829 | 11,831 | 6,856 |
Without a related allowance recorded, Interest Income Recognized | 159 | 92 | 400 | 279 |
With a related allowance recorded, Average Recorded Investment | 28 | 119 | 29 | 121 |
With a related allowance recorded, Interest Income Recognized | 0 | 2 | 2 | 5 |
Impaired Financing Receivable, Average Recorded Investment, Total | 11,714 | 6,948 | 11,860 | 6,977 |
Impaired Financing Receivable, Interest Income Recognized, Total | 159 | 94 | 402 | 284 |
Other Consumer |  |  |  |  |
Financing Receivable, Impaired [Line Items] |  |  |  |  |
Without a related allowance recorded, Recorded Investment | 29 |  | 29 |  | 111
Without a related allowance, Unpaid Principal Balance | 36 |  | 36 |  | 188
Without a related allowance recorded, Related Allowance | 0 |  | 0 |  | 0
With a related allowance recorded, Recorded Investment | 2 |  | 2 |  | 2
With a related allowance recorded, Unpaid Principal Balance | 2 |  | 2 |  | 2
Impaired Financing Receivable, Recorded Investment | 31 |  | 31 |  | 113
Impaired Financing Receivable, Unpaid Principal Balance, Total | 38 |  | 38 |  | 190
Impaired Financing Receivable, Related Allowance | 2 |  | 2 |  | $ 2
Without a related allowance recorded, Average Recorded Investment | 32 | 183 | 38 | 119 |
Without a related allowance recorded, Interest Income Recognized | 0 | 0 | 1 | 1 |
With a related allowance recorded, Average Recorded Investment | 2 | 2 | 2 | 2 |
With a related allowance recorded, Interest Income Recognized | 0 | 0 | 0 | 0 |
Impaired Financing Receivable, Average Recorded Investment, Total | 34 | 185 | 40 | 121 |
Impaired Financing Receivable, Interest Income Recognized, Total | $ 0 | $ 0 | $ 1 | $ 1 |

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