FAIR VALUE, Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Carrying Value [Member]
Financial assets [Abstract]
Net loans	$ 6,313,849	$ 4,901,329
Financial liabilities [Abstract]
Deposits	8,625,605	7,075,954
Short-term borrowings	179,000	146,200
Securities sold under agreement to repurchase, short-term	190,445	0
Other long-term debt	3,608	0
Subordinated debt held by unconsolidated subsidiary trusts	122,802	102,170
Fair Value [Member]
Financial assets [Abstract]
Net loans	6,377,803	4,935,140
Financial liabilities [Abstract]
Deposits	8,613,815	7,071,191
Short-term borrowings	179,000	146,200
Securities sold under agreement to repurchase, short-term	190,445	0
Other long-term debt	3,590	0
Subordinated debt held by unconsolidated subsidiary trusts	$ 122,802	$ 90,144