DEPOSITS - Summary of Certain Deposits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Non-interest bearing demand deposits	$ 1,538,331	$ 983,307
Savings and transaction accounts:
Savings deposits	312,702	234,508
Interest bearing demand deposits	3,498,474	3,150,512
Time deposits:
Other time deposits	239,582	281,934
Deposits of $100,000 to $250,000	271,337	291,805
Deposits of $250,000 or more	513,900	618,328
Total deposits	5,036,805	4,133,819
Demand Deposits [Member]
Savings and transaction accounts:
Interest bearing demand deposits	$ 2,160,953	$ 1,723,937