FAIR VALUE, Carrying Amounts and Estimated Fair Values of Other Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Carrying Value [Member]
Financial assets [Abstract]
Net loans	$ 4,775,576	$ 4,755,974
Financial liabilities [Abstract]
Deposits	7,119,062	6,873,474
Borrowings	33,700	301,300
Subordinated debt held by unconsolidated subsidiary trusts	102,152	102,146
Fair Value [Member]
Financial assets [Abstract]
Net loans	4,839,485	4,808,856
Financial liabilities [Abstract]
Deposits	7,117,700	6,871,098
Borrowings	33,700	301,300
Subordinated debt held by unconsolidated subsidiary trusts	$ 84,144	$ 84,680