New Accounting Standards (Policy)	9 Months Ended
Sep. 30, 2017
Accounting Changes and Error Corrections [Abstract]
Adoption of New Accounting Standards and New Accounting Standards Not Yet Adopted	Adoption of New Accounting Standards The Company adopted ASU 2016-09, “Stock Compensation – Improvements to Employee Share-Based Payment Accounting (Topic 718),” on a prospective basis as of January 1, 2017. This guidance requires entities to recognize the income tax effects for the difference between GAAP and federal income tax treatment (i.e., excess tax benefit or deficiency) of share-based awards in the income statement when the awards vest or are settled, rather than recording such effects in additional paid-in capital. As a result, the Company’s tax expense was reduced by approximately $11 million and $47 million in the third quarter and first nine months of 2017, respectively. Future effects will depend on the Company’s share price, restricted stock vesting, and the volume of equity incentive options exercised. ASU 2016-09 also provides entities with an accounting policy election to account for the impact of forfeitures of awards on compensation expense as they occur or continue with the current practice of estimating forfeitures at the grant date to determine the number of awards expected to vest and adjusting that estimate as necessary. The Company has elected to continue to follow the current practice of estimating forfeitures. New Accounting Standards Not Yet Adopted ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” provides new guidance on revenue recognition. The guidance clarifies that revenue from contracts with customers should be recognized in a manner that depicts the timing of the related transfer of goods or performance of services at an amount that reflects the expected consideration. The Financial Accounting Standards Board (FASB) has subsequently issued several amendments to the standard, including deferral of the effective date until January 1, 2018, clarification of principal versus agent considerations, narrow scope improvements, and other technical corrections. Entities may elect either full or modified retrospective transition. Full retrospective transition will require a cumulative effect adjustment to retained earnings as of the earliest comparative period presented. Modified retrospective transition will require a cumulative effect adjustment to retained earnings as of the beginning of the reporting period in which the entity first applies the new guidance. The Company plans to adopt the revenue recognition guidance in the first quarter of 2018 using the modified retrospective method. The guidance does not apply to the Company’s loans and securities. Accordingly, the Company does not expect an impact to net interest revenue. The Company believes the primary areas of potential impact for the Company are (i) the capitalization of costs to obtain a contract and (ii) gross versus net presentation of certain revenue streams in the income statement. The Company believes adoption of this guidance will likely alter the timing of recognition for costs to obtain a contract in the income statement. The next phase of the Company’s implementation work is to evaluate the disclosure provisions. The Company does not expect this guidance will have a material impact on its financial statements and EPS. ASU 2016-01, “Financial Instruments – Overall (Subtopic 825-10),” will be effective January 1, 2018 and requires a cumulative effect adjustment to the balance sheet as of the beginning of the year of initial application, except for certain changes that require prospective adoption. The main provisions of the guidance require: (i) equity investments to be measured at fair value, with changes in fair value recognized in net income, unless the equity method is applied or the equity investments do not have readily determinable fair values in which case a practical alternative may be elected; (ii) use of an exit price when measuring the fair value of financial instruments for disclosures; and (iii) separate presentation of financial assets and liabilities by measurement category and form of instrument on the balance sheet or in the accompanying notes. The Company does not expect this guidance will have a material impact on its financial statements and EPS. ASU 2016-02, “Leases (Topic 842),” amends the accounting for leases by lessees and lessors. The primary change from the new guidance is the recognition of right-of-use assets and lease liabilities by lessees for those leases classified as operating leases. Additional changes include accounting for lease origination and executory costs, required lessee reassessments during the lease term due to changes in circumstances, and expanded lease disclosures. ASU 2016-02 will become effective January 1, 2019, with early adoption permitted, and requires entities to apply the new guidance using a modified retrospective transition. Modified retrospective transition requires entities to apply the new guidance as of the beginning of the earliest comparative period presented in the financial statements in which the entity first applies the new standard. Certain transition relief is permitted if elected by the entity. The adoption of ASU 2016-02 will result in the Company recognizing a right-of-use asset and lease liability on the consolidated balance sheet based on the present value of remaining operating lease payments (see Note 14 of the Company’s 2016 Form 10-K for the undiscounted future annual minimum rental commitments for operating leases). The Company does not expect this guidance will have a material impact on its EPS. ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” provides new guidance for recognizing impairment of most debt instruments measured at amortized cost, including loans and held to maturity (HTM) debt securities. The new guidance will require estimating current expected credit losses (CECL) over the remaining life of an instrument or a portfolio of instruments with similar risk characteristics based on relevant information about past events, current conditions, and reasonable forecasts. The initial estimate of, and the subsequent changes in, CECL will be recognized as credit loss expense through current earnings and will be reflected as an allowance for credit losses offsetting the carrying value of the financial instrument(s) on the balance sheet. The new guidance also amends the OTTI model for AFS debt securities by requiring the use of an allowance, rather than directly reducing the carrying value of the security, and eliminating consideration of the length of time such security has been in an unrealized loss position as a factor in concluding whether a credit loss exists. ASU 2016-13 will become effective January 1, 2020, with early adoption permitted as of January 1, 2019. The new guidance will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the entity applies the new guidance except that a prospective transition is required for AFS debt securities for which an OTTI had been recognized before the effective date. The Company is currently evaluating the impact of this guidance on its financial statements and EPS. ASU 2017-08, “Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities,” shortens the amortization period for the premium on certain callable debt securities to the earliest call date. The amendments are applicable to any purchased individual debt security with an explicit and noncontingent call feature that is callable at a fixed price on a preset date. The amendments do not impact the accounting for callable debt securities held at a discount. ASU 2017-08 will become effective on January 1, 2019, with early adoption permitted including in an interim period. The amendments will be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact of adopting this guidance on its financial statements and EPS.

Adoption of New Accounting Standards

The Company adopted ASU 2016-09, “Stock Compensation – Improvements to Employee Share-Based Payment Accounting (Topic 718),” on a prospective basis as of January 1, 2017. This guidance requires entities to recognize the income tax effects for the difference between GAAP and federal income tax treatment (i.e., excess tax benefit or deficiency) of share-based awards in the income statement when the awards vest or are settled, rather than recording such effects in additional paid-in capital. As a result, the Company’s tax expense was reduced by approximately $11 million and $47 million in the third quarter and first nine months of 2017, respectively. Future effects will depend on the Company’s share price, restricted stock vesting, and the volume of equity incentive options exercised. ASU 2016-09 also provides entities with an accounting policy election to account for the impact of forfeitures of awards on compensation expense as they occur or continue with the current practice of estimating forfeitures at the grant date to determine the number of awards expected to vest and adjusting that estimate as necessary. The Company has elected to continue to follow the current practice of estimating forfeitures.

New Accounting Standards Not Yet Adopted

ASU 2014-09, “Revenue from Contracts with Customers (Topic 606),” provides new guidance on revenue recognition. The guidance clarifies that revenue from contracts with customers should be recognized in a manner that depicts the timing of the related transfer of goods or performance of services at an amount that reflects the expected consideration. The Financial Accounting Standards Board (FASB) has subsequently issued several amendments to the standard, including deferral of the effective date until January 1, 2018, clarification of principal versus agent considerations, narrow scope improvements, and other technical corrections. Entities may elect either full or modified retrospective transition. Full retrospective transition will require a cumulative effect adjustment to retained earnings as of the earliest comparative period presented. Modified retrospective transition will require a cumulative effect adjustment to retained earnings as of the beginning of the reporting period in which the entity first applies the new guidance.

The Company plans to adopt the revenue recognition guidance in the first quarter of 2018 using the modified retrospective method. The guidance does not apply to the Company’s loans and securities. Accordingly, the Company does not expect an impact to net interest revenue. The Company believes the primary areas of potential impact for the Company are (i) the capitalization of costs to obtain a contract and (ii) gross versus net presentation of certain revenue streams in the income statement. The Company believes adoption of this guidance will likely alter the timing of recognition for costs to obtain a contract in the income statement. The next phase of the Company’s implementation work is to evaluate the disclosure provisions. The Company does not expect this guidance will have a material impact on its financial statements and EPS.

ASU 2016-01, “Financial Instruments – Overall (Subtopic 825-10),” will be effective January 1, 2018 and requires a cumulative effect adjustment to the balance sheet as of the beginning of the year of initial application, except for certain changes that require prospective adoption. The main provisions of the guidance require: (i) equity investments to be measured at fair value, with changes in fair value recognized in net income, unless the equity method is applied or the equity investments do not have readily determinable fair values in which case a practical alternative may be elected; (ii) use of an exit price when measuring the fair value of financial instruments for disclosures; and (iii) separate presentation of financial assets and liabilities by measurement category and form of instrument on the balance sheet or in the accompanying notes. The Company does not expect this guidance will have a material impact on its financial statements and EPS.

ASU 2016-02, “Leases (Topic 842),” amends the accounting for leases by lessees and lessors. The primary change from the new guidance is the recognition of right-of-use assets and lease liabilities by lessees for those leases classified as operating leases. Additional changes include accounting for lease origination and executory costs, required lessee reassessments during the lease term due to changes in circumstances, and expanded lease disclosures. ASU 2016-02 will become effective January 1, 2019, with early adoption permitted, and requires entities to apply the new guidance using a modified retrospective transition. Modified retrospective transition requires entities to apply the new guidance as of the beginning of the earliest comparative period presented in the financial statements in which the entity first applies the new standard. Certain transition relief is permitted if elected by the entity. The adoption of ASU 2016-02 will result in the Company recognizing a right-of-use asset and lease liability on the consolidated balance sheet based on the present value of remaining operating lease payments (see Note 14 of the Company’s 2016 Form 10-K for the undiscounted future annual minimum rental commitments for operating leases). The Company does not expect this guidance will have a material impact on its EPS.

ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” provides new guidance for recognizing impairment of most debt instruments measured at amortized cost, including loans and held to maturity (HTM) debt securities. The new guidance will require estimating current expected credit losses (CECL) over the remaining life of an instrument or a portfolio of instruments with similar risk characteristics based on relevant information about past events, current conditions, and reasonable forecasts. The initial estimate of, and the subsequent changes in, CECL will be recognized as credit loss expense through current earnings and will be reflected as an allowance for credit losses offsetting the carrying value of the financial instrument(s) on the balance sheet. The new guidance also amends the OTTI model for AFS debt securities by requiring the use of an allowance, rather than directly reducing the carrying value of the security, and eliminating consideration of the length of time such security has been in an unrealized loss position as a factor in concluding whether a credit loss exists. ASU 2016-13 will become effective January 1, 2020, with early adoption permitted as of January 1, 2019. The new guidance will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the entity applies the new guidance except that a prospective transition is required for AFS debt securities for which an OTTI had been recognized before the effective date. The Company is currently evaluating the impact of this guidance on its financial statements and EPS.

ASU 2017-08, “Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities,” shortens the amortization period for the premium on certain callable debt securities to the earliest call date. The amendments are applicable to any purchased individual debt security with an explicit and noncontingent call feature that is callable at a fixed price on a preset date. The amendments do not impact the accounting for callable debt securities held at a discount. ASU 2017-08 will become effective on January 1, 2019, with early adoption permitted including in an interim period. The amendments will be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact of adopting this guidance on its financial statements and EPS.