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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 |
--- | --- | ---
Mar. 31, 2016 | Mar. 31, 2015 | Dec. 31, 2015
Financing Receivable, Impaired [Line Items] |  |  |
Without a related allowance recorded, Recorded Investment | $ 54,120 |  | $ 45,032
Without a related allowance, Unpaid Principal Balance | 66,949 |  | 50,286
Without a related allowance recorded, Related Allowance | 0 |  | 0
With a related allowance recorded, Recorded Investment | 6,082 |  | 618
With a related allowance recorded, Unpaid Principal Balance | 7,438 |  | 1,468
Impaired Financing Receivable, Recorded Investment | 60,202 |  | 45,650
Impaired Financing Receivable, Unpaid Principal Balance, Total | 74,387 |  | 51,754
Impaired Financing Receivable, Related Allowance | 2,213 |  | 37
Without a related allowance recorded, Average Recorded Investment | 56,028 | $ 48,285 |
Without a related allowance recorded, Interest Income Recognized | 547 | 375 |
With a related allowance recorded, Average Recorded Investment | 6,616 | 884 |
With a related allowance recorded, Interest Income Recognized | 40 | 9 |
Impaired Financing Receivable, Average Recorded Investment, Total | 62,644 | 49,169 |
Impaired Financing Receivable, Interest Income Recognized, Total | 587 | 384 |
Commercial Real Estate |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Without a related allowance recorded, Recorded Investment | 18,505 |  | 12,661
Without a related allowance, Unpaid Principal Balance | 26,493 |  | 13,157
Without a related allowance recorded, Related Allowance | 0 |  | 0
With a related allowance recorded, Recorded Investment | 0 |  | 0
With a related allowance recorded, Unpaid Principal Balance | 0 |  | 0
Impaired Financing Receivable, Recorded Investment | 18,505 |  | 12,661
Impaired Financing Receivable, Unpaid Principal Balance, Total | 26,493 |  | 13,157
Impaired Financing Receivable, Related Allowance | 0 |  | 0
Without a related allowance recorded, Average Recorded Investment | 18,605 | 22,627 |
Without a related allowance recorded, Interest Income Recognized | 199 | 164 |
With a related allowance recorded, Average Recorded Investment | 0 | 823 |
With a related allowance recorded, Interest Income Recognized | 0 | 8 |
Impaired Financing Receivable, Average Recorded Investment, Total | 18,605 | 23,450 |
Impaired Financing Receivable, Interest Income Recognized, Total | 199 | 172 |
Commercial and Industrial |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Without a related allowance recorded, Recorded Investment | 13,778 |  | 14,417
Without a related allowance, Unpaid Principal Balance | 14,750 |  | 15,220
Without a related allowance recorded, Related Allowance | 0 |  | 0
With a related allowance recorded, Recorded Investment | 4,850 |  | 0
With a related allowance recorded, Unpaid Principal Balance | 5,356 |  | 0
Impaired Financing Receivable, Recorded Investment | 18,628 |  | 14,417
Impaired Financing Receivable, Unpaid Principal Balance, Total | 20,106 |  | 15,220
Impaired Financing Receivable, Related Allowance | 2,027 |  | 0
Without a related allowance recorded, Average Recorded Investment | 15,513 | 10,847 |
Without a related allowance recorded, Interest Income Recognized | 149 | 62 |
With a related allowance recorded, Average Recorded Investment | 5,382 | 0 |
With a related allowance recorded, Interest Income Recognized | 32 | 0 |
Impaired Financing Receivable, Average Recorded Investment, Total | 20,895 | 10,847 |
Impaired Financing Receivable, Interest Income Recognized, Total | 181 | 62 |
Commercial Construction |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Without a related allowance recorded, Recorded Investment | 10,772 |  | 10,998
Without a related allowance, Unpaid Principal Balance | 13,974 |  | 14,200
Without a related allowance recorded, Related Allowance | 0 |  | 0
With a related allowance recorded, Recorded Investment | 1,116 |  | 500
With a related allowance recorded, Unpaid Principal Balance | 1,966 |  | 1,350
Impaired Financing Receivable, Recorded Investment | 11,888 |  | 11,498
Impaired Financing Receivable, Unpaid Principal Balance, Total | 15,940 |  | 15,550
Impaired Financing Receivable, Related Allowance | 154 |  | 3
Without a related allowance recorded, Average Recorded Investment | 10,782 | 7,704 |
Without a related allowance recorded, Interest Income Recognized | 64 | 53 |
With a related allowance recorded, Average Recorded Investment | 1,117 | 0 |
With a related allowance recorded, Interest Income Recognized | 6 | 0 |
Impaired Financing Receivable, Average Recorded Investment, Total | 11,899 | 7,704 |
Impaired Financing Receivable, Interest Income Recognized, Total | 70 | 53 |
Consumer Real Estate |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Without a related allowance recorded, Recorded Investment | 11,038 |  | 6,845
Without a related allowance, Unpaid Principal Balance | 11,703 |  | 7,521
Without a related allowance recorded, Related Allowance | 0 |  | 0
With a related allowance recorded, Recorded Investment | 114 |  | 116
With a related allowance recorded, Unpaid Principal Balance | 114 |  | 116
Impaired Financing Receivable, Recorded Investment | 11,152 |  | 6,961
Impaired Financing Receivable, Unpaid Principal Balance, Total | 11,817 |  | 7,637
Impaired Financing Receivable, Related Allowance | 30 |  | 32
Without a related allowance recorded, Average Recorded Investment | 11,102 | 7,073 |
Without a related allowance recorded, Interest Income Recognized | 135 | 96 |
With a related allowance recorded, Average Recorded Investment | 115 | 42 |
With a related allowance recorded, Interest Income Recognized | 2 | 1 |
Impaired Financing Receivable, Average Recorded Investment, Total | 11,217 | 7,115 |
Impaired Financing Receivable, Interest Income Recognized, Total | 137 | 97 |
Other Consumer |  |  |
Financing Receivable, Impaired [Line Items] |  |  |
Without a related allowance recorded, Recorded Investment | 27 |  | 111
Without a related allowance, Unpaid Principal Balance | 29 |  | 188
Without a related allowance recorded, Related Allowance | 0 |  | 0
With a related allowance recorded, Recorded Investment | 2 |  | 2
With a related allowance recorded, Unpaid Principal Balance | 2 |  | 2
Impaired Financing Receivable, Recorded Investment | 29 |  | 113
Impaired Financing Receivable, Unpaid Principal Balance, Total | 31 |  | 190
Impaired Financing Receivable, Related Allowance | 2 |  | $ 2
Without a related allowance recorded, Average Recorded Investment | 26 | 34 |
Without a related allowance recorded, Interest Income Recognized | 0 | 0 |
With a related allowance recorded, Average Recorded Investment | 2 | 19 |
With a related allowance recorded, Interest Income Recognized | 0 | 0 |
Impaired Financing Receivable, Average Recorded Investment, Total | 28 | 53 |
Impaired Financing Receivable, Interest Income Recognized, Total | $ 0 | $ 0 |

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- Definition Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524 + Details
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