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SECURITIES - Narrative (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2016 USD ($) security | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Investment Holdings [Line Items] |  |  |
Held-to-maturity securities, unrecognized holding gain | $ | $ 9,000 | $ 954 |
Proceeds from sales of securities available for sale | $ | 421,843 | 41,169 | $ 143,488
Available-for-sale securities, accumulated gross unrealized loss before tax | $ | 10,299 | 10,412 |
Securities available for sale, at fair value | $ | 1,209,537 | 1,154,457 |
Level 2 |  |  |
Investment Holdings [Line Items] |  |  |
Securities available for sale, at fair value | $ | $ 1,147,253 | 1,120,824 |
Municipal bonds and obligations |  |  |
Investment Holdings [Line Items] |  |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 3.40% |  |
Number of HTM investment securities in unrealized loss positions (security) | 53 |  |
Number of securities in the portfolio of HTM (security) | 199 |  |
Collateralized mortgage obligations |  |  |
Investment Holdings [Line Items] |  |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 2.70% |  |
Number of HTM investment securities in unrealized loss positions (security) | 1 |  |
Number of securities in the portfolio of HTM (security) | 9 |  |
Mortgage-backed Securities |  |  |
Investment Holdings [Line Items] |  |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 3.50% |  |
Number of HTM investment securities in unrealized loss positions (security) | 2 |  |
Number of securities in the portfolio of HTM (security) | 2 |  |
Corporate bonds | One Investment | Level 2 |  |  |
Investment Holdings [Line Items] |  |  |
Securities available for sale, at fair value | $ | $ 16,800 |  |
Debt securities | Municipal bonds and obligations |  |  |
Investment Holdings [Line Items] |  |  |
Available-for-sale securities in an unrealized loss position (security) | 16 |  |
Available for sale securities portfolio, number of securities (security) | 271 |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 7.10% |  |
Debt securities | Collateralized mortgage obligations |  |  |
Investment Holdings [Line Items] |  |  |
Available-for-sale securities in an unrealized loss position (security) | 71 |  |
Available for sale securities portfolio, number of securities (security) | 218 |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 1.00% |  |
Debt securities | Mortgage-backed Securities |  |  |
Investment Holdings [Line Items] |  |  |
Available-for-sale securities in an unrealized loss position (security) | 52 |  |
Available for sale securities portfolio, number of securities (security) | 105 |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 2.00% |  |
Debt securities | Corporate bonds |  |  |
Investment Holdings [Line Items] |  |  |
Available-for-sale securities in an unrealized loss position (security) | 3 |  |
Available for sale securities portfolio, number of securities (security) | 11 |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 2.90% |  |
Debt securities | Corporate bonds | One Investment |  |  |
Investment Holdings [Line Items] |  |  |
Available-for-sale securities, accumulated gross unrealized loss before tax | $ | $ 700 |  |
Securities available for sale, at fair value | $ | $ 17,500 |  |
Debt securities | Trust preferred securities |  |  |
Investment Holdings [Line Items] |  |  |
Available-for-sale securities in an unrealized loss position (security) | 1 |  |
Available for sale securities portfolio, number of securities (security) | 3 |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 4.60% |  |
Debt securities | Other bonds and obligations |  |  |
Investment Holdings [Line Items] |  |  |
Available-for-sale securities in an unrealized loss position (security) | 5 |  |
Available for sale securities portfolio, number of securities (security) | 9 |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 0.50% |  |
Marketable equity securities |  |  |
Investment Holdings [Line Items] |  |  |
Available-for-sale securities in an unrealized loss position (security) | 7 |  |
Available for sale securities portfolio, number of securities (security) | 27 |  |
Aggregate unrealized losses as a percentage of the amortized cost of the securities in unrealized loss positions | 11.40% |  |
Net unrealized holding gain on AFS securities |  |  |
Investment Holdings [Line Items] |  |  |
Other accumulated comprehensive income/(loss), before tax | $ | $ 25,176 | 6,316 |
Income tax benefit related to items of accumulated other comprehensive income/(loss) | $ | 9,636 | 2,437 |
Net unrealized holding gain on AFS securities | Securities Available for Sale |  |  |
Investment Holdings [Line Items] |  |  |
Other accumulated comprehensive income/(loss), before tax | $ | $ 16,200 | $ 5,300 |

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