FAIR VALUE, Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Carrying Value [Member]
Financial assets [Abstract]
Net loans	$ 4,885,117	$ 4,901,329
Financial liabilities [Abstract]
Deposits	7,336,877	7,075,954
Borrowings	0	146,200
Subordinated debt held by unconsolidated subsidiary trusts	102,177	102,170
Fair Value [Member]
Financial assets [Abstract]
Net loans	4,918,453	4,935,140
Financial liabilities [Abstract]
Deposits	7,331,201	7,071,191
Borrowings	0	146,200
Subordinated debt held by unconsolidated subsidiary trusts	$ 91,164	$ 90,144