JUNIOR SUBORDINATED DEBENTURES AND MANDATORILY REDEEMABLE TRUST PREFERRED SECURITIES (Details) (USD $) In Thousands, unless otherwise specified					12 Months Ended
	Dec. 31, 2012 subsidiary	Dec. 31, 2011	Dec. 31, 2012 Debentures Subject to Mandatory Redemption [Member]	Dec. 31, 2012 Debentures Subject to Mandatory Redemption [Member] Banner Capital Trusts [Member]	Dec. 31, 2012 Debentures Subject to Mandatory Redemption [Member] Banner Capital Trust II [Member]	Dec. 31, 2012 Debentures Subject to Mandatory Redemption [Member] Banner Capital Trust III [Member]	Dec. 31, 2012 Debentures Subject to Mandatory Redemption [Member] Banner Capital Trust IV [Member]	Dec. 31, 2012 Debentures Subject to Mandatory Redemption [Member] Banner Capital Trust V [Member]	Dec. 31, 2012 Debentures Subject to Mandatory Redemption [Member] Banner Capital Trust VI [Member]	Dec. 31, 2012 Debentures Subject to Mandatory Redemption [Member] Banner Capital Trust Vii [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Trust Preferred Securities [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Trust Preferred Securities [Member] Banner Capital Trust II [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Trust Preferred Securities [Member] Banner Capital Trust III [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Trust Preferred Securities [Member] Banner Capital Trust IV [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Trust Preferred Securities [Member] Banner Capital Trust V [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Trust Preferred Securities [Member] Banner Capital Trust VI [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Trust Preferred Securities [Member] Banner Capital Trust Vii [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Common Capital Securities [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Common Capital Securities [Member] Banner Capital Trust II [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Common Capital Securities [Member] Banner Capital Trust III [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Common Capital Securities [Member] Banner Capital Trust IV [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Common Capital Securities [Member] Banner Capital Trust V [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Common Capital Securities [Member] Banner Capital Trust VI [Member]	Dec. 31, 2012 Aggregate Liquidation Amount of Common Capital Securities [Member] Banner Capital Trust Vii [Member]
Schedule of Trust Preferred Securities [Line Items]
Number of wholly-owned Grantor Trusts	6
Grantor trusts amount of tier one risk based capital	$ 538,485	$ 572,036		$ 69,300
Grantor trusts percentage of tier one risk based capital				11.90%
Total TPS liability at par			123,716		15,464	15,465	15,465	25,774	25,774	25,774	120,000	15,000	15,000	15,000	25,000	25,000	25,000	3,716	464	465	465	774	774	774
Fair value adjustment			(50,653)
Total TPS liability at fair value			$ 73,063
Current Interest Rate			2.42%		3.69%	3.24%	3.19%	1.88%	1.93%	1.74%
Interest Rate Spread, Description					Three-month LIBOR	Three-month LIBOR	Three-month LIBOR	Three-month LIBOR	Three-month LIBOR	Three-month LIBOR
Interest Rate Spread					3.35%	2.90%	2.85%	1.57%	1.62%	1.38%
Interest Deferral Period (Consecutive Quarters)					5 years	5 years	5 years	5 years	5 years	5 years