Basis of presentation (Policies)	9 Months Ended
Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recent accounting pronouncements	In January 2014, the FASB issued ASU No. 2014-04, “Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure,” which clarifies when an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer loan. A creditor is considered to have received physical possession of residential real estate property collateralizing a consumer loan upon either: (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure; or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through a deed in lieu of foreclosure or through a similar legal agreement. The amendment also requires additional disclosures. The Company adopted ASU No. 2014-04 in the first quarter of 2015 and the adoption did not have a material impact on the Company’s results of operations, financial condition or liquidity. Revenues from contracts. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers: (Topic 606).” The core principle of the guidance in ASU No. 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that core principle, an entity should apply the following steps: (1) identify the contract/s with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when, or as, the entity satisfies a performance obligation. The Company plans to adopt ASU No. 2014-09 in the first quarter of 2018, but has not determined the method of adoption (full or modified retrospective application) nor the impact of adoption on its results of operations, financial condition or liquidity. Repurchase agreements. In June 2014, the FASB issued ASU No. 2014-11, “Transfers and Servicing (Topic 860): Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosure,” which changes the accounting for repurchase-to-maturity transactions and repurchase financing arrangements. It also requires additional disclosures about repurchase agreements and other similar transactions. The ASU requires a new disclosure for transactions economically similar to repurchase agreements in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets throughout the term of the transaction. The ASU also requires expanded disclosures about the nature of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings. The Company adopted ASU No. 2014-11 in the first quarter of 2015 and the adoption did not have a material impact on the Company’s results of operations, financial condition or liquidity. Debt issuance costs. In April 2015, the FASB issued ASU No. 2015-03, “Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs,” which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The Company plans to retrospectively adopt ASU No. 2015-03 in the first quarter 2016 and does not expect the adoption to have a material impact on the Company’s results of operations, financial condition or liquidity. In January 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-01, “Investments-Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects,” which permits entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met and investment amortization, net of tax credits, may be recognized in the income statement as a component of income taxes attributable to continuing operations. The amendments also require additional disclosures. The Company retrospectively adopted ASU No. 2014-01 in the first quarter of 2015. For prior periods, pursuant to ASU No. 2014-01, (a) amortization expense related to ASB’s qualifying investments in low income housing tax credits was reclassified from noninterest expense to income taxes; and (b) additional amortization, net of associated tax benefits was recognized in income taxes as a result of the adoption.

In January 2014, the FASB issued ASU No. 2014-04, “Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure,” which clarifies when an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer loan. A creditor is considered to have received physical possession of residential real estate property collateralizing a consumer loan upon either: (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure; or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through a deed in lieu of foreclosure or through a similar legal agreement. The amendment also requires additional disclosures.

The Company adopted ASU No. 2014-04 in the first quarter of 2015 and the adoption did not have a material impact on the Company’s results of operations, financial condition or liquidity.

Revenues from contracts. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers: (Topic 606).” The core principle of the guidance in ASU No. 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. To achieve that core principle, an entity should apply the following steps: (1) identify the contract/s with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when, or as, the entity satisfies a performance obligation.

The Company plans to adopt ASU No. 2014-09 in the first quarter of 2018, but has not determined the method of adoption (full or modified retrospective application) nor the impact of adoption on its results of operations, financial condition or liquidity.

Repurchase agreements. In June 2014, the FASB issued ASU No. 2014-11, “Transfers and Servicing (Topic 860): Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosure,” which changes the accounting for repurchase-to-maturity transactions and repurchase financing arrangements. It also requires additional disclosures about repurchase agreements and other similar transactions. The ASU requires a new disclosure for transactions economically similar to repurchase agreements in which the transferor retains substantially all of the exposure to the economic return on the transferred financial assets throughout the term of the transaction. The ASU also requires expanded disclosures about the nature of collateral pledged in repurchase agreements and similar transactions accounted for as secured borrowings.

The Company adopted ASU No. 2014-11 in the first quarter of 2015 and the adoption did not have a material impact on the Company’s results of operations, financial condition or liquidity.

Debt issuance costs. In April 2015, the FASB issued ASU No. 2015-03, “Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs,” which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts.

The Company plans to retrospectively adopt ASU No. 2015-03 in the first quarter 2016 and does not expect the adoption to have a material impact on the Company’s results of operations, financial condition or liquidity.

In January 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-01, “Investments-Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects,” which permits entities to make an accounting policy election to account for their investments in qualified affordable housing projects using the proportional amortization method if certain conditions are met and investment amortization, net of tax credits, may be recognized in the income statement as a component of income taxes attributable to continuing operations. The amendments also require additional disclosures.

The Company retrospectively adopted ASU No. 2014-01 in the first quarter of 2015. For prior periods, pursuant to ASU No. 2014-01, (a) amortization expense related to ASB’s qualifying investments in low income housing tax credits was reclassified from noninterest expense to income taxes; and (b) additional amortization, net of associated tax benefits was recognized in income taxes as a result of the adoption.