RECENT DEVELOPMENTS AND SIGNIFICANT EVENTS	9 Months Ended
Sep. 30, 2015
Recent Developments and Significant Events [Abstract]
RECENT DEVELOPMENTS AND SIGNIFICANT EVENTS	RECENT DEVELOPMENTS AND SIGNIFICANT EVENTS Acquisition of AmericanWest Bank As of the close of business on October 1, 2015, the Company completed its acquisition of Starbuck Bancshares, Inc. (Starbuck) and its subsidiary, AmericanWest Bank (AmericanWest), a Washington state chartered commercial bank headquartered in Spokane, Washington with 98 branches serving markets in Washington, Oregon, Idaho, California and Utah. On that date Starbuck merged with and into Banner and AmericanWest merged with and into Banner Bank. The merged banks are operating as Banner Bank. Pursuant to the previously announced terms of the merger, the equityholders of Starbuck received an aggregate of $130.0 million in cash and 13.23 million shares of Banner common stock and nonvoting common stock. At the closing date, the combined company had approximately $9.9 billion in assets and 203 branches. (See Note 4, Business Combinations, below in this Form 10-Q for additional information regarding this acquisition). Acquisition of Siuslaw Financial Group, Inc. As of the close of business on March 6, 2015, the Company completed its acquisition of Siuslaw Financial Group (Siuslaw) and its subsidiary, Siuslaw Bank, an Oregon state chartered commercial bank with ten branches in Lane County, Oregon, including Eugene, Oregon. On that date Siuslaw was merged with and into Banner Corporation and Siuslaw Bank was merged with and into Banner Bank. The operating results produced by the ten branches acquired in the Siuslaw acquisition are included in Banner's financial results beginning March 7, 2015 and the combined banks are operating as Banner Bank. (See Note 4, Business Combinations, below in this Form 10-Q for additional information regarding this acquisition).

RECENT DEVELOPMENTS AND SIGNIFICANT EVENTS

Acquisition of AmericanWest Bank

As of the close of business on October 1, 2015, the Company completed its acquisition of Starbuck Bancshares, Inc. (Starbuck) and its subsidiary, AmericanWest Bank (AmericanWest), a Washington state chartered commercial bank headquartered in Spokane, Washington with 98 branches serving markets in Washington, Oregon, Idaho, California and Utah. On that date Starbuck merged with and into Banner and AmericanWest merged with and into Banner Bank. The merged banks are operating as Banner Bank. Pursuant to the previously announced terms of the merger, the equityholders of Starbuck received an aggregate of $130.0 million in cash and 13.23 million shares of Banner common stock and nonvoting common stock. At the closing date, the combined company had approximately $9.9 billion in assets and 203 branches. (See Note 4, Business Combinations, below in this Form 10-Q for additional information regarding this acquisition).

Acquisition of Siuslaw Financial Group, Inc.

As of the close of business on March 6, 2015, the Company completed its acquisition of Siuslaw Financial Group (Siuslaw) and its subsidiary, Siuslaw Bank, an Oregon state chartered commercial bank with ten branches in Lane County, Oregon, including Eugene, Oregon. On that date Siuslaw was merged with and into Banner Corporation and Siuslaw Bank was merged with and into Banner Bank. The operating results produced by the ten branches acquired in the Siuslaw acquisition are included in Banner's financial results beginning March 7, 2015 and the combined banks are operating as Banner Bank. (See Note 4, Business Combinations, below in this Form 10-Q for additional information regarding this acquisition).