COMMITMENTS, CONTINGENCIES, AND GUARANTEES (Other Commitments) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Other Commitments [Line Items]
Lines of credit outstanding	$ 122,700	$ 89,600
Total commitments	33,846,354	32,378,134
Commitments to extend credit
Other Commitments [Line Items]
Other commitments	32,068,222	30,685,478
Letters of credit
Other Commitments [Line Items]
Letters of credit	1,653,301	1,592,726
Commitments to sell loans
Other Commitments [Line Items]
Other commitments	44,588	21,341
Unsecured revolving lines of credit
Other Commitments [Line Items]
Lines of credit outstanding	26,854	24,922
Recourse exposure on sold loans
Other Commitments [Line Items]
Other commitments	$ 53,389	$ 53,667