BANNER CORPORATION (PARENT COMPANY ONLY) (Statements of Financial Position) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
ASSETS
Other assets	$ 40,781	$ 37,255
Total assets	4,265,564	4,257,312
LIABILITIES AND STOCKHOLDERS' EQUITY
Junior subordinated debentures at fair value	73,063	49,988
Stockholders’ equity	506,919	532,450	511,472	405,128
Total Liabilities and Stockholders' Equity	4,265,564	4,257,312
Banner Corporation
ASSETS
Cash	36,884	73,033
Investment in trust equities	3,716	3,716
Investment in subsidiaries	556,125	532,561
Other assets	2,601	1,207
Total assets	599,326	610,517
LIABILITIES AND STOCKHOLDERS' EQUITY
Miscellaneous liabilities	6,401	2,106
Deferred tax liability	12,943	25,973
Junior subordinated debentures at fair value	73,063	49,988
Stockholders’ equity	506,919	532,450
Total Liabilities and Stockholders' Equity	$ 599,326	$ 610,517