BANNER CORPORATION (PARENT COMPANY ONLY) (Statements of Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
INTEREST INCOME:
Interest-bearing deposits	$ 496,891	$ 481,301	$ 468,919
OTHER INCOME (EXPENSE):
Other income	12,875	6,821	8,624
Interest on other borrowings	(467)	(603)	(330)
Other expenses	(24,236)	(22,712)	(27,387)
Income before provision for income taxes	246,594	142,453	183,132
PROVISION FOR INCOME TAXES	45,546	26,525	36,854
Net Income (Loss) Attributable to Parent	201,048	115,928	146,278
Banner Corporation
INTEREST INCOME:
Interest-bearing deposits	97	112	98
OTHER INCOME (EXPENSE):
Dividend income from subsidiaries	99,788	87,748	119,333
Equity in undistributed income of subsidiaries	112,814	36,401	35,134
Other income	146	62	33
Interest on other borrowings	(8,780)	(7,204)	(6,574)
Other expenses	(7,391)	(3,530)	(4,045)
Income before provision for income taxes	196,674	113,589	143,979
PROVISION FOR INCOME TAXES	(4,374)	(2,339)	(2,299)
Net Income (Loss) Attributable to Parent	$ 201,048	$ 115,928	$ 146,278