BORROWED FUNDS - Summary of Borrowed Funds (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Principal, Short-term borrowings	$ 110,000	$ 125,000
Principal, Long-term borrowings	592,706	702,550
Total borrowings	$ 702,706	$ 827,550
Weighted average rate on short-term borrowings	1.16%	2.06%
Weighted average rate on long-term borrowings	2.55%	2.72%
Weighted average rate	2.33%	2.62%
Advances from the FHLB
Debt Instrument [Line Items]
Principal, Short-term borrowings	$ 110,000	$ 125,000
Principal, Long-term borrowings	$ 494,859	$ 605,501
Weighted average rate on short-term borrowings	1.16%	2.06%
Weighted average rate on long-term borrowings	1.90%	2.16%
Paycheck Protection Program Liquidity Facility ("PPPLF")
Debt Instrument [Line Items]
Principal, Long-term borrowings	$ 624	$ 0
Weighted average rate on long-term borrowings	0.35%	0.00%
Subordinated borrowings
Debt Instrument [Line Items]
Principal, Long-term borrowings	$ 74,366	$ 74,232
Weighted average rate on long-term borrowings	7.00%	7.00%
Junior subordinated borrowing - Trust I
Debt Instrument [Line Items]
Principal, Long-term borrowings	$ 15,464	$ 15,464
Weighted average rate on long-term borrowings	2.11%	3.76%
Junior subordinated borrowing - Trust II
Debt Instrument [Line Items]
Principal, Long-term borrowings	$ 7,393	$ 7,353
Weighted average rate on long-term borrowings	1.95%	3.59%

Amount of short-term and long-term debt and lease obligation.

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