SBM ACQUISITION - NARRATIVE (Details) - USD ($)		3 Months Ended		6 Months Ended
	Oct. 16, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill, Period Increase (Decrease)		$ 960,000
Assets		3,910,386,000		$ 3,910,386,000		$ 3,709,344,000
Loans and Leases Receivable, Net Amount		2,561,583,000		2,561,583,000		2,469,040,000
Deposits		$ 2,773,487,000		$ 2,773,487,000		$ 2,726,379,000
Common stock, outstanding (shares)		10,281,113		10,281,113		10,220,478
Merger and acquisition costs		$ 177,000	$ 128,000	$ 821,000	$ 863,000
Business Combination Provisional Information Initial Accounting Incomplete Adjustment Impact on Earnings				0
SBM Financial, Inc. [Member]
Business Acquisition [Line Items]
Goodwill, Period Increase (Decrease)				(960,000)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets				137,000
Consideration transferred	$ 136,676,000
Cash	26,125,000
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 108,561,000
Business Combination Provisional Information Initial Accounting Incomplete Adjustment Other Assets				157,000
Business Combination Provisional Information Initial Accounting Incomplete Adjustment Deferred Tax Asset				$ 666,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	2,749,762
Share Price	$ 39.48
Nonqualified Stock Options [Member] | SBM Financial, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned	$ 1,990,000