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Allowance for Loan Losses and Credit Quality of Loans, Credit Quality by Loan Class (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | $ 6,584,773 | $ 6,198,057
Commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,317,174 | 1,242,701
Home Equity [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 494,771 | 507,784
Consumer Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,234,809 | 2,149,441
Residential Mortgage Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,321,695 | 1,262,614
Originated Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 6,183,082 | 5,697,963
Originated Loans [Member] | Commercial Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,360,001 | 2,075,697
Originated Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,245,016 | 1,970,912
Originated Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 63,336 | 40,724
Originated Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 51,649 | 64,056
Originated Loans [Member] | Commercial Credit Exposure [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans |  | 5
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 753,779 | 653,570
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 708,567 | 616,829
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 30,337 | 7,750
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 14,875 | 28,991
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans |  | 0
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,536,542 | 1,351,789
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,481,926 | 1,288,409
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 28,264 | 31,053
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 26,352 | 32,327
Originated Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans |  | 0
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 35,546 | 37,916
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 31,142 | 36,762
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,294 | 25
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,110 | 1,124
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans |  | 5
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 34,134 | 32,422
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 23,381 | 28,912
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,441 | 1,896
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 8,312 | 1,614
Originated Loans [Member] | Commercial Credit Exposure [Member] | Agricultural Real Estate [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans |  | 0
Originated Loans [Member] | Business Banking Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 480,955 | 472,687
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 468,898 | 458,864
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 12,057 | 13,823
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 480,955 | 472,687
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 468,898 | 458,864
Originated Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 12,057 | 13,823
Originated Loans [Member] | Consumer Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,190,903 | 2,086,436
Originated Loans [Member] | Consumer Credit Exposure [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,182,114 | 2,078,286
Originated Loans [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 8,789 | 8,150
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,671,051 | 1,566,675
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,665,444 | 1,562,031
Originated Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 5,607 | 4,644
Originated Loans [Member] | Consumer Credit Exposure [Member] | Home Equity [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 454,899 | 456,657
Originated Loans [Member] | Consumer Credit Exposure [Member] | Home Equity [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 451,822 | 453,278
Originated Loans [Member] | Consumer Credit Exposure [Member] | Home Equity [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 3,077 | 3,379
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 64,953 | 63,104
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 64,848 | 62,977
Originated Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 105 | 127
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,151,223 | 1,063,143
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,143,974 | 1,055,055
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 7,249 | 8,088
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,151,223 | 1,063,143
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,143,974 | 1,055,055
Originated Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 7,249 | 8,088
Acquired Loans [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 401,691 | 500,094
Acquired Loans [Member] | Commercial Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 146,209 | 186,736
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 141,073 | 175,854
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 923 | 1,307
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 4,213 | 8,370
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans |  | 1,205
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 39,575 | 49,447
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 37,825 | 48,194
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 425 | 76
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,325 | 1,177
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans |  | 0
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 106,634 | 137,289
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Pass [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 103,248 | 127,660
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Special Mention [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 498 | 1,231
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Substandard [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,888 | 7,193
Acquired Loans [Member] | Commercial Credit Exposure [Member] | Commercial Real Estate [Member] | Doubtful [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans |  | 1,205
Acquired Loans [Member] | Business Banking Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 41,104 | 50,882
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Non-classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 38,236 | 47,347
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,868 | 3,535
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 41,104 | 50,882
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Non-classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 38,236 | 47,347
Acquired Loans [Member] | Business Banking Credit Exposure [Member] | Business Banking [Member] | Classified [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,868 | 3,535
Acquired Loans [Member] | Consumer Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 43,906 | 63,005
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 43,531 | 62,671
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 375 | 334
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,218 | 8,693
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,195 | 8,646
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Indirect [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 23 | 47
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Home Equity [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 39,872 | 51,127
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Home Equity [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 39,544 | 50,860
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Home Equity [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 328 | 267
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,816 | 3,185
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 2,792 | 3,165
Acquired Loans [Member] | Consumer Credit Exposure [Member] | Direct [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 24 | 20
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 170,472 | 199,471
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 168,901 | 196,508
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 1,571 | 2,963
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 170,472 | 199,471
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Performing [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | 168,901 | 196,508
Acquired Loans [Member] | Residential Mortgage Credit Exposure [Member] | Residential Mortgage [Member] | Nonperforming [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Net Loans | $ 1,571 | $ 2,963

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- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524 + Details
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