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PARENT COMPANY STATEMENTS, Condensed Statements of Condition (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | --- | --- | ---
Assets [Abstract] |  |  |  |
Cash and cash equivalents | $ 221,038 | $ 173,857 | $ 153,210 | $ 138,396
Investment in and advances to [Abstract] |  |  |  |
Other assets | 249,488 | 180,188 |  |
Total assets | 10,746,198 | 8,666,437 | 8,552,669 |
Liabilities and shareholders' equity [Abstract] |  |  |  |
Accrued interest and other liabilities | 180,567 | 144,013 |  |
Borrowings | 122,814 | 102,170 |  |
Shareholders' equity | 1,635,315 | 1,198,100 | 1,140,647 | 987,904
Total liabilities and shareholders' equity | 10,746,198 | 8,666,437 |  |
Parent Company [Member] |  |  |  |
Assets [Abstract] |  |  |  |
Cash and cash equivalents | 84,460 | 151,127 | $ 97,317 | $ 106,957
Investment securities | 4,322 | 3,628 |  |
Investment in and advances to [Abstract] |  |  |  |
Bank subsidiary | 1,511,780 | 1,116,554 |  |
Non-bank subsidiaries | 169,341 | 35,566 |  |
Other assets | 9,150 | 10,345 |  |
Total assets | 1,779,053 | 1,317,220 |  |
Liabilities and shareholders' equity [Abstract] |  |  |  |
Accrued interest and other liabilities | 20,924 | 16,950 |  |
Borrowings | 122,814 | 102,170 |  |
Shareholders' equity | 1,635,315 | 1,198,100 |  |
Total liabilities and shareholders' equity | $ 1,779,053 | $ 1,317,220 |  |

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