Investments (Policy)	9 Months Ended
Investments (Policy)	Sep. 30, 2018
Investments [Abstract]
Investments	Management systematically evaluates securities for impairment on a quarterly basis. Based upon application of accounting guidance for subsequent measurement in ASC Topic 320 (ASC Section 320-10-35), management assesses whether (a) the Corporation has the intent to sell a security being evaluated and (b) it is more likely than not that the Corporation will be required to sell the security prior to its anticipated recovery. If neither applies, then declines in the fair values of securities below their cost that are considered other-than-temporary declines are split into two components. The first is the loss attributable to declining credit quality. Credit losses are recognized in earnings as realized losses in the period in which the impairment determination is made. The second component consists of all other losses, which are recognized in other comprehensive loss. In estimating other than temporary impairment (“OTTI”) losses, management considers (1) the length of time and the extent to which the fair value has been less than cost, (2) adverse conditions specifically related to the security, an industry, or a geographic area, (3) the historic and implied volatility of the fair value of the security, (4) changes in the rating of the security by a rating agency, (5) recoveries or additional declines in fair value subsequent to the balance sheet date, (6) failure of the issuer of the security to make scheduled interest or principal payments, and (7) the payment structure of the debt security and the likelihood of the issuer being able to make payments that increase in the future. Management also monitors cash flow projections for securities that are considered beneficial interests under the guidance of ASC Subtopic 325-40, Investments – Other – Beneficial Interests in Securitized Financial Assets, (ASC Section 325-40-35). Further discussion about the evaluation of securities for impairment can be found in Item 2 of Part I of this report under the heading “Investment Securities”.

Disclosure of accounting policy for investments in financial assets, including marketable securities (debt and equity securities with readily determinable fair values), investments accounted for under the equity method and cost method, securities borrowed and loaned, and repurchase and resale agreements. For marketable securities, the disclosure may include the entity's accounting treatment for transfers between investment categories and how the fair values for such securities are determined. Also, for all investments, an entity may describe its policy for assessing, recognizing and measuring impairment of the investment.