COMMITMENTS AND CONTINGENCIES (Balances of Commitments and Contingencies) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Commitments with off-balance sheet risk:
Total commitments with off-balance sheet risk	$ 4,770,584	$ 4,900,930
Commitments to Extend Credit
Commitments with off-balance sheet risk:
Total commitments with off-balance sheet risk	4,605,213	4,691,272
Standby Letters of Credit
Commitments with off-balance sheet risk:
Total commitments with off-balance sheet risk	$ 165,371	$ 209,658