SUBSEQUENT EVENT (Details) - USD ($) $ in Thousands	Oct. 06, 2015	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Assets [Abstract]
Assets		$ 4,035,977	$ 3,747,013	$ 3,625,619
Loans		3,270,915	3,016,085
Other real estate owned		2,832	11,243
Cash and cash equivalents		90,731	72,878	$ 69,682	$ 170,863
Other assets		34,638	34,976
Liabilities		3,461,265	3,188,282
Federal Home Loan Bank advances		711,500	$ 707,500
Cornerstone
Assets [Abstract]
Assets		243,000
Loans		183,000
Other real estate owned		0
Marketable securities		35,000
Cash and cash equivalents		5,000
Other assets		20,000
Liabilities		216,000
Customer deposits		206,000
Federal Home Loan Bank advances		$ 8,000
Subsequent event. | Forecast | Cornerstone
SUBSEQUENT EVENT
Total cash payment	$ 32,300