BORROWED FUNDS - Summary of Borrowed Funds (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Short-term borrowings
Amount	$ 649,498	$ 394,480
Weighted Average Rate	1.43%	0.93%
Long-term borrowings
Amount	$ 180,223	$ 142,116
Weighted Average Rate	2.47%	1.69%
Total borrowings	$ 829,721	$ 536,596
Weighted Average Rate	1.66%	1.13%
Advances from the FHLB
Short-term borrowings
Amount	$ 608,792	$ 372,700
Weighted Average Rate	1.49%	0.97%
Long-term borrowings
Amount	$ 137,190	$ 137,116
Weighted Average Rate	1.72%	1.59%
Other borrowings
Short-term borrowings
Amount	$ 40,706	$ 21,780
Weighted Average Rate	0.59%	0.29%
Subordinated borrowings
Long-term borrowings
Amount	$ 38,033	$ 0
Weighted Average Rate	4.88%	0.00%
Junior subordinated borrowings
Long-term borrowings
Amount	$ 5,000	$ 5,000
Weighted Average Rate	4.89%	4.41%