FAIR VALUE, Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Carrying Value [Member]
Financial assets [Abstract]
Net loans	$ 4,267,959	$ 4,190,865
Financial liabilities [Abstract]
Deposits	6,148,110	5,935,264
Borrowings	558,100	338,000
Subordinated debt held by unconsolidated subsidiary trusts	102,140	102,122
Fair Value [Member]
Financial assets [Abstract]
Net loans	4,317,941	4,251,565
Financial liabilities [Abstract]
Deposits	6,147,341	5,935,690
Borrowings	558,100	338,000
Subordinated debt held by unconsolidated subsidiary trusts	$ 87,170	$ 85,189