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Allowance for Loan Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | $ 5,002,925 | $ 3,850,597
Loans, Past Due | 60,008 | 21,119
Loans, Non-performing | 35,382 | 12,457
Total Loans | 5,062,933 | 3,871,716
Commercial Real Estate |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 2,145,655 | 1,674,930
Loans, Past Due | 20,948 | 7,306
Loans, Non-performing | 8,719 | 4,435
Total Loans | 2,166,603 | 1,682,236
Commercial and Industrial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 1,244,802 | 991,136
Loans, Past Due | 12,028 | 3,002
Loans, Non-performing | 9,279 | 1,622
Total Loans | 1,256,830 | 994,138
Commercial Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 401,084 | 214,174
Loans, Past Due | 12,360 | 1,974
Loans, Non-performing | 8,753 | 1,974
Total Loans | 413,444 | 216,148
Residential Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 631,085 | 485,465
Loans, Past Due | 8,287 | 4,121
Loans, Non-performing | 5,629 | 2,336
Total Loans | 639,372 | 489,586
Home Equity |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 465,055 | 414,303
Loans, Past Due | 5,790 | 4,260
Loans, Non-performing | 2,902 | 2,059
Total Loans | 470,845 | 418,563
Installment and Other Consumer |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 73,486 | 65,111
Loans, Past Due | 453 | 456
Loans, Non-performing | 100 | 31
Total Loans | 73,939 | 65,567
Consumer Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 6,579 | 2,508
Loans, Past Due | 0 | 0
Loans, Non-performing | 0 | 0
Total Loans | 6,579 | 2,508
Loans Held for Sale |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 35,179 | 2,970
Loans, Past Due | 142 | 0
Loans, Non-performing | 0 | 0
Total Loans | 35,321 | 2,970
30-59 Days Past Due |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 22,001 | 6,448
30-59 Days Past Due | Commercial Real Estate |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 11,602 | 2,548
30-59 Days Past Due | Commercial and Industrial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 2,453 | 1,227
30-59 Days Past Due | Commercial Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 3,517 | 0
30-59 Days Past Due | Residential Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 1,728 | 565
30-59 Days Past Due | Home Equity |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 2,365 | 1,756
30-59 Days Past Due | Installment and Other Consumer |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 242 | 352
30-59 Days Past Due | Consumer Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 0 | 0
30-59 Days Past Due | Loans Held for Sale |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 94 | 0
60-89 Days Past Due |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 2,625 | 2,214
60-89 Days Past Due | Commercial Real Estate |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 627 | 323
60-89 Days Past Due | Commercial and Industrial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 296 | 153
60-89 Days Past Due | Commercial Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 90 | 0
60-89 Days Past Due | Residential Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 930 | 1,220
60-89 Days Past Due | Home Equity |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 523 | 445
60-89 Days Past Due | Installment and Other Consumer |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 111 | 73
60-89 Days Past Due | Consumer Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | 0 | 0
60-89 Days Past Due | Loans Held for Sale |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Past Due | $ 48 | $ 0

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