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Allowance for Loan Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Details) - USD ($) $ in Thousands | Jun. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | $ 5,730,426 | $ 5,563,123
Total nonaccrual loans | 36,669 | 42,635
Total past due | 50,513 | 52,089
Total Loans | 5,780,939 | 5,615,212
Commercial Real Estate |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 2,653,680 | 2,479,513
Total nonaccrual loans | 7,199 | 16,172
Total past due | 10,962 | 18,963
Total Loans | 2,664,642 | 2,498,476
Commercial and Industrial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 1,381,657 | 1,391,475
Total nonaccrual loans | 17,418 | 8,071
Total past due | 19,626 | 9,560
Total Loans | 1,401,283 | 1,401,035
Commercial Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 424,254 | 450,410
Total nonaccrual loans | 2,313 | 4,927
Total past due | 2,500 | 5,474
Total Loans | 426,754 | 455,884
Residential Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 694,800 | 689,635
Total nonaccrual loans | 7,056 | 9,918
Total past due | 11,343 | 12,347
Total Loans | 706,143 | 701,982
Home Equity Loan |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 479,190 | 476,866
Total nonaccrual loans | 2,642 | 3,439
Total past due | 5,770 | 5,418
Total Loans | 484,960 | 482,284
Installment and Other Consumer |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 69,756 | 65,525
Total nonaccrual loans | 41 | 108
Total past due | 312 | 327
Total Loans | 70,068 | 65,852
Consumer Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 3,969 | 5,906
Total nonaccrual loans | 0 | 0
Total past due | 0 | 0
Total Loans | 3,969 | 5,906
Loans Held for Sale |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Loans, Current | 23,120 | 3,793
Total nonaccrual loans | 0 | 0
Total past due | 0 | 0
Total Loans | 23,120 | 3,793
30 to 59 Days Past Due |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 10,824 | 6,598
30 to 59 Days Past Due | Commercial Real Estate |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 2,846 | 2,032
30 to 59 Days Past Due | Commercial and Industrial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 1,454 | 1,061
30 to 59 Days Past Due | Commercial Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 187 | 547
30 to 59 Days Past Due | Residential Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 3,506 | 1,312
30 to 59 Days Past Due | Home Equity Loan |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 2,620 | 1,470
30 to 59 Days Past Due | Installment and Other Consumer |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 211 | 176
30 to 59 Days Past Due | Consumer Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 0 | 0
30 to 59 Days Past Due | Loans Held for Sale |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 0 | 0
60 to 89 Days Past Due |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 3,020 | 2,856
60 to 89 Days Past Due | Commercial Real Estate |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 917 | 759
60 to 89 Days Past Due | Commercial and Industrial |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 754 | 428
60 to 89 Days Past Due | Commercial Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 0 | 0
60 to 89 Days Past Due | Residential Mortgage |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 781 | 1,117
60 to 89 Days Past Due | Home Equity Loan |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 508 | 509
60 to 89 Days Past Due | Installment and Other Consumer |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 60 | 43
60 to 89 Days Past Due | Consumer Construction |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | 0 | 0
60 to 89 Days Past Due | Loans Held for Sale |  |
Financing Receivable, Recorded Investment, Past Due [Line Items] |  |
Total past due | $ 0 | $ 0

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