BUSINESS COMBINATIONS BUSINESS COMBINATIONS (Schedule of Acquisition-Related Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	$ 2,207	$ (494)	$ 7,741	$ 1,530
Salary and Employee Benefits [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	227	0	443	0
Occupancy and Equipment [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	5	70	55	99
Advertising and Marketing [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	151	(108)	221	130
Information and Computer Data Services [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	301	(335)	807	297
Payment and Card Processing Expenses [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	16	(205)	16	66
Professional Services [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	1,185	55	5,411	674
Miscellaneous Other Noninterest Expense [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	322	29	788	264
Six Oregon Branches [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	0	(494)	0	1,530
Siuslaw Financial Group, Inc [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	340	0	1,867	0
Starbuck Bancshares, Inc [Member]
Business Acquisition [Line Items]
Acquisition-related costs recognized in other operating expenses:	$ 1,867	$ 0	$ 5,874	$ 0