BUSINESS COMBINATIONS BUSINESS COMBINATIONS (Schedule of Components of Acquisition) (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Mar. 06, 2015	Jun. 20, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Fair value of liabilities assumed:
Goodwill			$ 21,148		$ 21,148		$ 0	$ 0
Acquisition bargain purchase gain			$ 0	$ 0	$ 0	$ 9,079
Siuslaw Financial Group, Inc [Member]
Business Acquisition [Line Items]
Acquisition Date	Mar. 06, 2015
Consideration Transferred
Cash paid	$ 5,806
Fair value of common shares issued	58,100
Total consideration	63,906
Fair value of assets acquired:
Cash and cash equivalents	84,405
Securities—available-for-sale	12,865
Loans receivable	247,098
Real estate owned, held for sale	2,525
Property and equipment	8,127
Core deposit intangible	3,895
Other assets	11,391
Total assets acquired	370,306
Fair value of liabilities assumed:
Deposits	316,406
Junior subordinated debentures	5,959
Other liabilities	5,183
Total liabilities assumed	327,548
Net assets acquired	42,758
Goodwill	21,148
Business Combination, Acquired Receivables, Gross Contractual Amount	$ 252,200
Six Oregon Branches [Member]
Business Acquisition [Line Items]
Acquisition Date		Jun. 20, 2014
Consideration Transferred
Total consideration		$ 0
Fair value of assets acquired:
Cash and cash equivalents		127,557
Loans receivable		87,923
Property and equipment		3,079
Core deposit intangible		2,372
Other assets		275
Total assets acquired		221,206
Fair value of liabilities assumed:
Deposits		212,085
Other liabilities		42
Total liabilities assumed		212,127
Net assets acquired		9,079
Acquisition bargain purchase gain		9,079
Business Combination, Acquired Receivables, Gross Contractual Amount		$ 88,300