Commitments and Contingencies	9 Months Ended
Sep. 30, 2012
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	Commitments and Contingencies: On March 22, 2012, Sterling and its subsidiary Sterling Savings Bank were named as defendants in a purported class action lawsuit filed by a Washington customer of Sterling Savings Bank in King County, Washington, Superior Court, and on May 25, 2012, Sterling Savings Bank was named a defendant in a similar purported class action lawsuit filed on behalf of a customer in the U.S. District Court of Oregon. These suits challenged the manner in which overdraft fees were charged and the disclosures related to posting order of debit card and ATM transactions, and alleged claims for breach of contract, breach of the covenant of good faith and fair dealing, unconscionability, conversion, unjust enrichment, and a violation of state consumer protection laws. The two suits encompassed claims on behalf of Sterling Savings Bank customers from the five states in which Sterling Savings Bank presently conducts business. On October 17, 2012, Sterling announced the dismissal of the plaintiffs' claims. Securities Class Action Litigation. On December 11, 2009, a putative securities class action was filed in the United States District Court for the Eastern District of Washington against Sterling and certain of our current and former officers. The court appointed a lead plaintiff on March 9, 2010. On June 18, 2010, the lead plaintiff filed a consolidated complaint (the “Complaint”). The Complaint purports to be brought on behalf of a class of persons who purchased or otherwise acquired Sterling's stock during the period from July 23, 2008 to October 15, 2009. The Complaint alleges that defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 by failing to disclose the extent of Sterling's delinquent commercial real estate, construction and land development loans, properly record losses for impaired loans, and properly reserve for loan losses, thereby causing Sterling's stock price to be artificially inflated during the purported class period. Plaintiffs seek unspecified damages and attorneys' fees and costs. Sterling believes the lawsuit is without merit and intends to defend against it vigorously. On August 30, 2010, Sterling moved to dismiss the Complaint. On March 2, 2011, after complete briefing, the court held a hearing on the motion to dismiss. The court has not yet issued an order on the motion, but recently indicated that it intends to do so in the near future. Failure by Sterling to obtain a favorable resolution of the claims set forth in the complaint could have a material adverse effect on our business, results of operations and financial condition. Currently, a loss resulting from these claims is not considered probable or reasonably estimable in amount. ERISA Class Action Litigation. On January 20 and 22, 2010, two putative class action complaints were filed in the United States District Court for the Eastern District of Washington against Sterling Financial Corporation and Sterling Savings Bank (collectively, “Sterling”), as well as certain of Sterling's current and former officers and directors. The two complaints were merged in a Consolidated Amended Complaint (the “Complaint”) filed on July 16, 2010 in the same court. The Complaint does not name all of the individuals named in the prior complaints, but it is expected that additional defendants will be added. The Complaint alleges that the defendants breached their fiduciary duties under sections 404 and 405 of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), with respect to the Sterling Savings Bank Employee Savings and Investment Plan (the “401(k) Plan”) and the FirstBank Northwest Employee Stock Ownership Plan (“ESOP”) (collectively, the "Plans”). Specifically, the Complaint alleges that the defendants breached their duties by investing assets of the Plans in Sterling's securities when it was imprudent to do so, and by investing such assets in Sterling securities when defendants knew or should have known that the price of those securities was inflated due to misrepresentations and omissions about Sterling's business practices. The business practices at issue include alleged over-reliance on risky construction loans; alleged inadequate loan reserves; alleged spiking increases in nonperforming assets, nonperforming loans, classified assets, and 90+-day delinquent loans; alleged inadequate accounting for rising loan payment shortfalls; alleged unsafe and unsound banking practices; and a capital base that was allegedly inadequate to withstand the significant deterioration in the real estate markets. The putative class periods are October 22, 2007 to the present for the 401(k) Plan class, and October 22, 2007 to November 14, 2008 for the ESOP class. The Complaint seeks damages of an unspecified amount and attorneys' fees and costs. On September 26, 2012, Sterling received a letter from the U.S. Department of Labor (the “Department of Labor”) containing similar allegations as those set forth in the Complaint, demanding that the violations alleged in the Department of Labor's letter be corrected and notifying Sterling that the Department of Labor may take legal action in connection with such allegations, including assessing a civil money penalty. Sterling believes the Complaint, and Department of Labor allegations, are without merit and intends to defend against them vigorously. A hearing on the motion to dismiss the Complaint occurred on March 22, 2011, with the court indicating that it would take the motion under submission. The court has not yet issued an order on the motion, but recently indicated that it intends to do so in the near future. Failure by Sterling to obtain a favorable resolution of the claims set forth in the Complaint or in the letter from the Department of Labor could have a material adverse effect on Sterling's business, results of operations, and financial condition. Currently, a loss resulting from these claims is not considered probable or reasonably estimable in amount. On June 29, 2012, Sterling Bank entered into a definitive agreement for the sale of its Montana operations to Eagle Bancorp Montana, Inc. and its wholly owned subsidiary American Federal Savings Bank. The transaction is subject to customary closing conditions, and is expected to be completed during the fourth quarter of 2012.

Commitments and Contingencies:

On March 22, 2012, Sterling and its subsidiary Sterling Savings Bank were named as defendants in a purported class action lawsuit filed by a Washington customer of Sterling Savings Bank in King County, Washington, Superior Court, and on May 25, 2012, Sterling Savings Bank was named a defendant in a similar purported class action lawsuit filed on behalf of a customer in the U.S. District Court of Oregon. These suits challenged the manner in which overdraft fees were charged and the disclosures related to posting order of debit card and ATM transactions, and alleged claims for breach of contract, breach of the covenant of good faith and fair dealing, unconscionability, conversion, unjust enrichment, and a violation of state consumer protection laws. The two suits encompassed claims on behalf of Sterling Savings Bank customers from the five states in which Sterling Savings Bank presently conducts business. On October 17, 2012, Sterling announced the dismissal of the plaintiffs' claims.

Securities Class Action Litigation. On December 11, 2009, a putative securities class action was filed in the United States District Court for the Eastern District of Washington against Sterling and certain of our current and former officers. The court appointed a lead plaintiff on March 9, 2010. On June 18, 2010, the lead plaintiff filed a consolidated complaint (the “Complaint”). The Complaint purports to be brought on behalf of a class of persons who purchased or otherwise acquired Sterling's stock during the period from July 23, 2008 to October 15, 2009. The Complaint alleges that defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 by failing to disclose the extent of Sterling's delinquent commercial real estate, construction and land development loans, properly record losses for impaired loans, and properly reserve for loan losses, thereby causing Sterling's stock price to be artificially inflated during the purported class period. Plaintiffs seek unspecified damages and attorneys' fees and costs. Sterling believes the lawsuit is without merit and intends to defend against it vigorously. On August 30, 2010, Sterling moved to dismiss the Complaint. On March 2, 2011, after complete briefing, the court held a hearing on the motion to dismiss. The court has not yet issued an order on the motion, but recently indicated that it intends to do so in the near future. Failure by Sterling to obtain a favorable resolution of the claims set forth in the complaint could have a material adverse effect on our business, results of operations and financial condition. Currently, a loss resulting from these claims is not considered probable or reasonably estimable in amount.

ERISA Class Action Litigation. On January 20 and 22, 2010, two putative class action complaints were filed in the United States District Court for the Eastern District of Washington against Sterling Financial Corporation and Sterling Savings Bank (collectively, “Sterling”), as well as certain of Sterling's current and former officers and directors. The two complaints were merged in a Consolidated Amended Complaint (the “Complaint”) filed on July 16, 2010 in the same court. The Complaint does not name all of the individuals named in the prior complaints, but it is expected that additional defendants will be added. The Complaint alleges that the defendants breached their fiduciary duties under sections 404 and 405 of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), with respect to the Sterling Savings Bank Employee Savings and Investment Plan (the “401(k) Plan”) and the FirstBank Northwest Employee Stock Ownership Plan (“ESOP”) (collectively, the "Plans”). Specifically, the Complaint alleges that the defendants breached their duties by investing assets of the Plans in Sterling's securities when it was imprudent to do so, and by investing such assets in Sterling securities when defendants knew or should have known that the price of those securities was inflated due to misrepresentations and omissions about Sterling's business practices. The business practices at issue include alleged over-reliance on risky construction loans; alleged inadequate loan reserves; alleged spiking increases in nonperforming assets, nonperforming loans, classified assets, and 90+-day delinquent loans; alleged inadequate accounting for rising loan payment shortfalls; alleged unsafe and unsound banking practices; and a capital base that was allegedly inadequate to withstand the significant deterioration in the real estate markets. The putative class periods are October 22, 2007 to the present for the 401(k) Plan class, and October 22, 2007 to November 14, 2008 for the ESOP class. The Complaint seeks damages of an unspecified amount and attorneys' fees and costs. On September 26, 2012, Sterling received a letter from the U.S. Department of Labor (the “Department of Labor”) containing similar allegations as those set forth in the Complaint, demanding that the violations alleged in the Department of Labor's letter be corrected and notifying Sterling that the Department of Labor may take legal action in connection with such allegations, including assessing a civil money penalty. Sterling believes the Complaint, and Department of Labor allegations, are without merit and intends to defend against them vigorously. A hearing on the motion to dismiss the Complaint occurred on March 22, 2011, with the court indicating that it would take the motion under submission. The court has not yet issued an order on the motion, but recently indicated that it intends to do so in the near future. Failure by Sterling to obtain a favorable resolution of the claims set forth in the Complaint or in the letter from the Department of Labor could have a material adverse effect on Sterling's business, results of operations, and financial condition. Currently, a loss resulting from these claims is not considered probable or reasonably estimable in amount.

On June 29, 2012, Sterling Bank entered into a definitive agreement for the sale of its Montana operations to Eagle Bancorp Montana, Inc. and its wholly owned subsidiary American Federal Savings Bank. The transaction is subject to customary closing conditions, and is expected to be completed during the fourth quarter of 2012.