Summary of Significant Accounting Policies (Policies)

3 Months Ended

6 Months Ended

Jun. 30, 2018

Jun. 30, 2018

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

Revenue Recognition, Policy [Policy Text Block]

Revenue Recognition The Corporation recognizes revenue in accordance with ASC 606, "Revenue from Contracts with Customers." ASC 606 requires the Corporation to follow a five step process: (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. Revenue recognition under ASC 606 depicts 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 the goods or services.

Business combination

Business combinations

The Corporation accounts for its acquisitions using the purchase accounting method. Purchase accounting requires the total purchase price to be allocated to the estimated fair values of assets acquired and liabilities assumed, including certain intangible assets that must be recognized. Typically, this allocation results in the purchase price exceeding the fair value of net assets acquired, which is recorded as goodwill. Core deposit intangibles are a measure of the value of checking, money market and savings deposits acquired in business combinations accounted for under the purchase method. Core deposit intangibles and other identified intangibles with finite useful lives are amortized using the straight line method over their estimated useful lives of up to ten years.

Loans that the Corporation acquires in connection with acquisitions are recorded at fair value with no carryover of the related allowance for credit losses. Fair value of the loans involves estimating the amount and timing of principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The excess of cash flows expected at acquisition over the estimated fair value is referred to as the accretable discount and is recognized into interest income over the remaining life of the loan when there is a reasonable expectation about the amount and timing of such cash flows. If a reasonable expectation on the amount or timing of such cash flows can't be determined, accretion of the fair value discount for nonperforming loans will be recognized using the cost recovery method of accounting.

The difference between contractually required payments at acquisition and the cash flows expected to be collected at acquisition is referred to as the non-accretable discount. The non-accretable discount includes estimated future credit losses expected to be incurred over the life of the loan. Subsequent decreases to the expected cash flows will require the Corporation to evaluate the need for an additional allowance for credit losses. Subsequent improvement in expected cash flows will result in the reversal of a corresponding amount of the non-accretable discount which the Corporation will then reclassify as accretable discount that will be recognized into interest income over the remaining life of the loan.

The Corporation accounts for performing loans acquired in business combinations using the contractual cash flows method of recognizing discount accretion based on the acquired loans’ contractual cash flows. Purchased performing loans are recorded at fair value, including credit, interest, and liquidity discounts. The fair value discount is accreted as an adjustment to yield over the estimated lives of the loans. There is no allowance for loan losses established at the acquisition date for purchased performing loans. A provision for loan losses is recorded for any further deterioration in these loans subsequent to the acquisition.

New Accounting Pronouncements, Policy

New Accounting Pronouncements Adopted

Standard	Description	Date of adoption	Effect on financial statements
ASU 2018-02 Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income	The FASB issued an amendment to allow a reclassification from accumulated other comprehensive income to retained earnings for the stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017. The amendments in this update are effective for all entities for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption of the update is permitted and should be applied in the period of adoption or retrospectively to each period in which the effect of the change in the U.S. federal corporate income tax rate related to the Tax Cut and Jobs Act of 2017 is recognized.	1st Quarter 2018	The Corporation has elected to early adopt this amendment. During the quarter, the Corporation reclassified approximately $14 million from accumulated other comprehensive income to retained earnings as a result of the Tax Cuts and Jobs Act. No material impact on results of operations, financial position, or liquidity. See Consolidated Statements of Comprehensive Income and the Statement of Changes in Stockholders' Equity.
ASU 2017-12 Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities	The FASB issued an amendment to better align a company’s financial reporting for hedging activities with the economic objectives of those activities for both financial (e.g., interest rate) and commodity risks. The provisions create more transparency around how economic results are presented, both on the face of the financial statements and in the footnotes. It also contains targeted improvements to simplify the application of hedge accounting guidance. This amendment is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Entities should apply the amendment on a modified retrospective transition method in which the cumulative effect of the change will be recognized within equity in the consolidated balance sheet as of the date of adoption. Early adoption is permitted, including in an interim period. If an entity early adopts in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes the interim period.	1st Quarter 2018	The Corporation has elected to early adopt this amendment. No material impact on results of operations, financial position, or liquidity. See Note 10 for expanded disclosures.
ASU 2017-07 Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost	The FASB issued an amendment to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost, including a requirement that employers disaggregate the service cost component from the other components of net benefit cost. In addition, the amendments provide explicit guidance on how to present the service cost component and the other components of net benefit cost in the income statement and allow only the service cost component of net benefit cost to be eligible for capitalization. This amendment is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented and prospectively only for the capitalization component. Early adoption is permitted, but should be within the first interim period if interim financial statements are issued.	1st Quarter 2018	No impact on results of operations, financial position, or liquidity. The Update required retrospective restatement. For the full year 2017, the Corporation reclassified approximately $9 million from personnel expense to other noninterest expense for the non-service cost components of net periodic pension cost and net periodic postretirement benefit cost. See Note 14 for expanded disclosure.
ASU 2017-01 Business Combinations (Topic 805): Clarifying the Definition of a Business	The FASB issued amendments to clarify the definition of a business in order to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets versus businesses. The new standard narrows the definition of a business by adding three principal clarifications if: (1) substantially all the fair value of the gross assets in the asset group is concentrated in either a single identifiable asset or group of similar identifiable assets the transaction does not involve a business, (2) the asset group does not include a minimum of an input and a substantive process, it does not represent a business, and (3) the integrated set of activities (including its inputs and processes) does not create, or have the ability to create, goods or services to customers, investment income (e,g. dividends or interest) or other revenues, then it is not a business. The overall intention is to provide consistency in applying the guidance, reduce the costs of application, and make the definition of a business more operable.	1st Quarter 2018	No material impact on results of operations, financial position, or liquidity.
ASU 2016-18 Statement of Cash Flows (Topic 230): Restricted Cash	The FASB issued an amendment to improve GAAP by providing guidance on the presentation of restricted cash or restricted cash equivalents in the statement of cash flows, in order to reduce diversity in practice. The amendment requires that a statement of cash flow explain the change during the period in the total cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included in cash and cash equivalents when reconciling the beginning and end of period total amounts shown on the statement of cash flow. This amendment is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented. Early adoption is permitted, including in an interim period.	1st Quarter 2018	No impact on results of operations, financial position, or liquidity. See Consolidated Statements of Cash Flows.

Standard	Description	Date of adoption	Effect on financial statements
ASU 2016-16 Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory	The FASB issued an amendment requiring an entity to recognize income tax consequences on an intra-entity transfer of an asset other than inventory at the time the transaction occurs. This amendment is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment by means of a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. Early adoption is permitted for all entities in the first interim period if an entity issues interim financial statements.	1st Quarter 2018	No material impact on results of operations, financial position, or liquidity.
ASU 2016-15 Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments	The FASB issued an amendment to provide clarification on where to classify cash flows involving certain cash receipts and cash payments. Under the new guidance, cash payments for debt prepayment or debt extinguishment costs should be classified as cash outflows from financing activities. The new guidance also details the specific classification of contingent consideration cash payments made after a business combination depending on the timing of payments. Lastly, cash proceeds received from corporate owned life insurance policies (including bank owned life insurance) should be classified as cash inflows from investing, while the cash payments for the premiums may be classified as cash outflows from investing, operating, or a combination of both. This amendment is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities should apply the amendment retrospectively to each period presented. Early adoption is permitted, including in an interim period; however, all of the amendments must be adopted in the same period.	1st Quarter 2018	No material impact on results of operations, financial position, or liquidity.
ASU 2016-01 Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities	The FASB issued an amendment to address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. This amendment supersedes the guidance to classify equity securities with readily determinable fair values into different categories, requires equity securities to be measured at fair value with changes in the fair value recognized through net income, and simplifies the impairment assessment of equity investments without readily determinable fair values. The amendment requires public business entities that are required to disclose the fair value of financial instruments measured at amortized cost on the balance sheet to measure that fair value using the exit price notion. The amendment requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option. The amendment requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or in the accompanying notes to the financial statements. The amendment reduces diversity in current practice by clarifying that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available for sale securities in combination with the entity’s other deferred tax assets. This amendment is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Entities are required to apply the amendment by means of a cumulative-effect adjustment as of the beginning of the fiscal year of adoption, with the exception of the amendment related to equity securities without readily determinable fair values, which should be applied prospectively to equity investments that exist as of the date of adoption.	1st Quarter 2018	The Corporation has adopted this amendment and is using the cumulative-effect adjustment as of the beginning of the fiscal year of adoption. No material impact on the result of operations, financial position or liquidity. In 2008, the Corporation received Visa Class B restricted shares as part of Visa’s initial public offering. Based on the existing transfer restriction and the uncertainty of the covered litigation, the approximately 119 thousand Class B shares remaining that the Corporation owned as of June 30, 2018 are carried at a zero cost basis. See Consolidated Statements of Comprehensive Income and Note 13 Fair Value Measurements.
ASU 2014-09 Revenue from Contracts with Customers (Topic 606)	The FASB issued an amendment to clarify the principles for recognizing revenue and to develop a common revenue standard. The standard outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The core principle of the revenue model is that “an entity recognizes 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.” In applying the revenue model to contracts within its scope, 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 standard applies to all contracts with customers except those that are within the scope of other topics in the FASB Codification. The standard also requires significantly expanded disclosures about revenue recognition. The FASB continues to release new accounting guidance related to the adoption of this standard, which could impact the Corporation's preliminary materiality analysis and may change the conclusions reached as to the application of this new guidance. The amendment was originally to be effective for annual reporting periods beginning after December 15, 2016 (including interim reporting periods within those periods); however, in July 2015, the FASB approved a one year deferral of the effective date to December 31, 2017.	1st Quarter 2018	The Corporation chose to adopt this amendment using the modified retrospective approach with no material impact on the Corporation's results of operations, financial position, or liquidity. See Note 17 for expanded disclosure requirements.