INVESTMENT SECURITIES - Held-to-maturity (Details) - USD ($) |
3 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2016 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Investments, Debt and Equity Securities [Abstract] | ||||
| Held-to-maturity securities transferred to available-for-sale securities | $ 52,400,000 | |||
| Held-to-maturity securities transferred to available-for-sale securities, unrealized holding gains | $ 1,800,000 | $ 1,825,000 | $ 0 | $ 0 |
| Amortized cost and fair values of investment securities held-to-maturity | ||||
| Amortized Cost | 0 | 52,859,000 | ||
| Unrealized Gain | 1,699,000 | |||
| Unrealized Loss | (88,000) | |||
| Fair Value | $ 0 | 54,470,000 | ||
| Municipal securities | ||||
| Amortized cost and fair values of investment securities held-to-maturity | ||||
| Amortized Cost | 52,859,000 | |||
| Unrealized Gain | 1,699,000 | |||
| Unrealized Loss | (88,000) | |||
| Fair Value | $ 54,470,000 | |||