COMMITMENTS AND CONTINGENT LIABILITIES - Schedule of Guarantor Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments to extend credit	$ 2,486,949	$ 1,671,419
Unused home equity lines of credit	262,089	112,310
Financial standby letters of credit	29,232	24,596
Mortgage interest rate lock commitments	$ 288,490	$ 81,833