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Allowance for Credit Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Details) - USD ($) $ in Thousands | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Financing Receivable, Past Due [Line Items] |  |  |
Current |  | $ 7,145,326 | $ 7,055,361
Past due |  | 101,419 | 81,791
Non - performing |  | 73,799 | 54,057
Total |  | 7,246,745 | 7,137,152
30 to 59 Days Past Due |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 18,211 | 17,992
60 to 89 Days Past Due |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 4,117 | 5,985
90 Days Past Due |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due | [1] | 5,294 | 3,757
Commercial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total |  | 5,620,415 | 5,512,796
Commercial | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current |  | 2,901,375 | 3,025,505
Past due |  | 53,614 | 34,087
Non - performing |  | 46,533 | 25,356
Total |  | 2,954,989 | 3,059,592
Commercial | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current |  | 1,516,639 | 1,466,460
Past due |  | 7,582 | 14,069
Non - performing |  | 4,505 | 10,911
Total |  | 1,524,221 | 1,480,529
Commercial | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current |  | 388,122 | 367,204
Past due |  | 2,080 | 2,856
Non - performing |  | 571 | 737
Total |  | 390,202 | 370,060
Commercial | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current |  | 1,048,241 | 830,735
Past due |  | 22,223 | 16,055
Non - performing |  | 11,316 | 9,863
Total |  | 1,070,464 | 846,790
Commercial | 30 to 59 Days Past Due | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 6,381 | 7,749
Commercial | 30 to 59 Days Past Due | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 463 | 126
Commercial | 30 to 59 Days Past Due | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 576 | 956
Commercial | 30 to 59 Days Past Due | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 6,758 | 5,093
Commercial | 60 to 89 Days Past Due | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 0 | 71
Commercial | 60 to 89 Days Past Due | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 0 | 1,589
Commercial | 60 to 89 Days Past Due | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 0 | 1,163
Commercial | 60 to 89 Days Past Due | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 3,381 | 1,099
Commercial | 90 Days Past Due | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due | [1] | 700 | 911
Commercial | 90 Days Past Due | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due | [1] | 2,615 | 1,443
Commercial | 90 Days Past Due | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due | [1] | 933 | 0
Commercial | 90 Days Past Due | Business banking |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due | [1] | 768 | 0
Consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Total |  | 1,626,330 | 1,624,356
Consumer | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current |  | 1,211,865 | 1,283,591
Past due |  | 15,203 | 11,616
Non - performing |  | 10,616 | 6,063
Total |  | 1,227,069 | 1,295,207
Consumer | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current |  | 79,083 | 81,866
Past due |  | 717 | 3,108
Non - performing |  | 258 | 1,127
Total |  | 79,800 | 84,974
Consumer | 30 to 59 Days Past Due | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 3,859 | 2,620
Consumer | 30 to 59 Days Past Due | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 174 | 1,448
Consumer | 60 to 89 Days Past Due | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 646 | 1,758
Consumer | 60 to 89 Days Past Due | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due |  | 91 | 305
Consumer | 90 Days Past Due | Consumer real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due | [1] | 83 | 1,175
Consumer | 90 Days Past Due | Other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past due | [1] | $ 195 | $ 228
[1] | Represents acquired loans that were recorded at fair value at the acquisition date and remain performing at March 31, 2020 and December 31, 2019.

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