Introduction to Notes to Condensed Consolidated Financial Statements (Unaudited) Accounting Pronouncement Changes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Description of Transition Method			We have elected to early adopt the requirements of the amended standard in the third quarter of 2016 and are therefore required to report the impacts as though adopted on January 1, 2016. Accordingly, we recognized additional income tax benefits of approximately $13 million and $11 million for the quarter and nine months ended September 30, 2016, respectively. In addition, we recognized the additional income tax benefits and cash paid by directly withholding shares for tax withholding purposes of $29 million for the nine months ended September 30, 2016 as an increase in net cash flows provided by operating activities of continuing operations, and an increase in net cash flows used in financing activities of continuing operations. There is no change to our accounting policy with respect to estimation of forfeitures.
Income Tax Expense (Benefit)	$ 492	$ 592	$ 1,548	$ 1,748
ASU 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Description			In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, which amends the accounting for employee share-based payment transactions to require recognition of the tax effects resulting from the settlement of stock-based awards as income tax expense or benefit in the income statement in the reporting period in which they occur. The ASU also requires that all tax-related cash flows resulting from share-based payments, including the excess tax benefits related to the settlement of stock-based awards, be classified as cash flows from operating activities, and that cash paid by directly withholding shares for tax withholding purposes be classified as a financing activity in the statement of cash flows. In addition, the ASU also allows companies to make an accounting policy election to either estimate the number of awards that are expected to vest, consistent with current U.S. GAAP, or account for forfeitures when they occur. The new standard is effective for annual reporting periods beginning after December 15, 2016 with early adoption permitted. We have elected to early adopt the requirements of the amended standard in the third quarter of 2016 and are therefore required to report the impacts as though adopted on January 1, 2016. Accordingly, we recognized additional income tax benefits of approximately $13 million and $11 million for the quarter and nine months ended September 30, 2016, respectively. In addition, we recognized the additional income tax benefits and cash paid by directly withholding shares for tax withholding purposes of $29 million for the nine months ended September 30, 2016 as an increase in net cash flows provided by operating activities of continuing operations, and an increase in net cash flows used in financing activities of continuing operations. There is no change to our accounting policy with respect to estimation of forfeitures.
New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income Tax Expense (Benefit)	$ (13)		$ (11)
Net Cash Provided by (Used in) Operating Activities			29
Net Cash Provided by (Used in) Financing Activities			$ (29)