SUBSEQUENT EVENT Subsequent Event (Details) - Skagit Bank [Member] - Subsequent Event [Member]	Nov. 01, 2018 USD ($) bank_branch shares
Subsequent Event [Line Items]
Business Combination, Consideration Transferred, Shares Issued for Each Aquiree Share | shares	5.6664
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	$ 919,000,000
Business Combination, Acquired Receivable, Fair Value	604,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits	$ 819,000,000
Business Combination, Number of Retail Branches Acquired | bank_branch	11
Business Combination, Combined Assets	$ 11,400,000,000