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Pro Forma Summary (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
2017 acquisitions |  |  |
Pro Forma Information |  |  |
Net interest income and non-interest income | $ 462,603 | $ 436,678 |
Net income | $ 114,187 | 124,373 |
2016 acquisitions |  |  |
Pro Forma Information |  |  |
Net interest income and non-interest income |  | 424,242 | $ 392,252
Net income |  | $ 120,929 | $ 116,577

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