Debt and Credit Facility Schedule of Carrying Amounts of Senior Notes (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 22,225	$ 12,404
Less Current Portion	331	483
Total Long-Term Debt, Net	$ 21,894	11,921
Senior Unsecured Notes Due In April 2021
Debt Instrument [Line Items]
Stated interest rate	4.50%
Senior Unsecured Notes	$ 995	995
Senior Unsecured Notes Due In December 2016
Debt Instrument [Line Items]
Stated interest rate	3.05%
Senior Unsecured Notes	$ 700	700
Senior Unsecured Notes Due In December 2021
Debt Instrument [Line Items]
Stated interest rate	4.40%
Senior Unsecured Notes	$ 1,248	1,248
Senior Unsecured Notes Due In December 2041
Debt Instrument [Line Items]
Stated interest rate	5.65%
Senior Unsecured Notes	$ 998	998
Senior Unsecured Notes Due in April 2019
Debt Instrument [Line Items]
Stated interest rate	2.05%
Senior Unsecured Notes	$ 499	499
Senior Unsecured Notes Due in April 2024
Debt Instrument [Line Items]
Stated interest rate	3.70%
Senior Unsecured Notes	$ 1,748	1,747
Senior Unsecured Notes Due in April 2044
Debt Instrument [Line Items]
Stated interest rate	4.80%
Senior Unsecured Notes	$ 1,747	1,747
Senior Unsecured Notes Due In February 2020
Debt Instrument [Line Items]
Stated interest rate	2.35%
Senior Unsecured Notes	$ 499	499
Senior Unsecured Notes Due in February 2025
Debt Instrument [Line Items]
Stated interest rate	3.50%
Senior Unsecured Notes	$ 1,748	1,748
Senior Unsecured Notes Due in February 2045
Debt Instrument [Line Items]
Stated interest rate	4.50%
Senior Unsecured Notes	$ 1,740	1,740
Senior Unsecured Notes Due in September 2018
Debt Instrument [Line Items]
Stated interest rate	1.85%
Senior Unsecured Notes	$ 1,000	0
Senior Unsecured Notes Due in September 2020
Debt Instrument [Line Items]
Stated interest rate	2.55%
Senior Unsecured Notes	$ 1,996	0
Senior Unsecured Notes Due in September 2022
Debt Instrument [Line Items]
Stated interest rate	3.25%
Senior Unsecured Notes	$ 999	0
Senior Unsecured Notes Due in March 2026
Debt Instrument [Line Items]
Stated interest rate	3.65%
Senior Unsecured Notes	$ 2,739	0
Senior Unsecured Notes Due in September 2035
Debt Instrument [Line Items]
Stated interest rate	4.60%
Senior Unsecured Notes	$ 997	0
Senior Unsecured Notes Due in March 2046
Debt Instrument [Line Items]
Stated interest rate	4.75%
Senior Unsecured Notes	$ 2,241	0
Senior Unsecured Notes Due in September 2018, 2020, 2022, 2035 and March 2026 and 2046 [Member]
Debt Disclosure- March and Sept Notes (Narrative) [Abstract]
Debt Instrument, Face Amount	10,000
Debt Issuance Cost	$ 70
Debt Disclosure-Issuers Option to Redeem Anytime [Abstract]
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	101.00%
Debt Disclosure-Issuer's Pre-maturity Option to Redeem [Abstract]
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	101.00%
Debt Disclosure-Bondholders' Contingent PUT option for redemption [Abstract]
Debt Instrument, Redemption Price, Percentage	100.00%
Convertible Senior Notes Due In May 2016
Debt Instrument [Line Items]
Stated interest rate	1.625%
Convertible Senior Notes	$ 331	$ 483

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