Borrowings (Pre-Swap Borrowing) (Details 2) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 37,343	$ 39,737
Less: net unamortized discount	840	853
Add: fair value adjustment	904	792
Long-Term Debt, including current portion	37,407	39,675
Less: current maturities	5,286	4,601
Total long-term debt (excluding current portion)	32,122	35,073
U.S. dollar notes and debentures
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	29,420	31,404
1.41% Notes and Debentures, maturing in 2015-2016
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 5,274	9,254
Debt instrument, stated interest rate percentage (as a percent)	1.41%
3.91% Notes and Debentures, maturing in 2017-2018
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 8,773	6,835
Debt instrument, stated interest rate percentage (as a percent)	3.91%
2.24% Notes and Debentures, maturing in 2019-2021
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 6,613	6,555
Debt instrument, stated interest rate percentage (as a percent)	2.24%
1.88% Notes and Debentures, maturing in 2022
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 1,000	1,000
Debt instrument, stated interest rate percentage (as a percent)	1.88%
3.38% Notes and Debentures, maturing in 2023
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 1,500	1,500
Debt instrument, stated interest rate percentage (as a percent)	3.38%
3.63% Notes and Debentures, maturing in 2024
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 2,000	2,000
Debt instrument, stated interest rate percentage (as a percent)	3.63%
7.00% Notes and Debentures, maturing in 2025
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 600	600
Debt instrument, stated interest rate percentage (as a percent)	7.00%
6.22% Notes and Debentures, maturing in 2027
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 469	469
Debt instrument, stated interest rate percentage (as a percent)	6.22%
6.50% Notes and Debentures, maturing in 2028
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 313	313
Debt instrument, stated interest rate percentage (as a percent)	6.50%
5.88% Notes and Debentures, maturing in 2032
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 600	600
Debt instrument, stated interest rate percentage (as a percent)	5.88%
8.00% Notes and Debentures, maturing in 2038
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 83	83
Debt instrument, stated interest rate percentage (as a percent)	8.00%
5.60% Notes and Debentures, maturing in 2039
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 745	745
Debt instrument, stated interest rate percentage (as a percent)	5.60%
4.00% Notes and Debentures, maturing in 2042
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 1,107	1,107
Debt instrument, stated interest rate percentage (as a percent)	4.00%
7.00% Notes and Debentures, maturing in 2045
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 27	27
Debt instrument, stated interest rate percentage (as a percent)	7.00%
7.13% Notes and Debentures, maturing in 2096
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 316	316
Debt instrument, stated interest rate percentage (as a percent)	7.13%
1.8% Euros maturing in 2015 - 2025
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 5,033	5,463
Debt instrument, stated interest rate percentage (as a percent)	1.80%
2.7% Pound sterling maturing in 2017 - 2020
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 1,597	1,176
Debt instrument, stated interest rate percentage (as a percent)	2.70%
0.5% Japanese yen maturing in 2017-2019
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 734	733
Debt instrument, stated interest rate percentage (as a percent)	0.50%
6.3% Swiss francs maturing in 2020
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 10	162
Debt instrument, stated interest rate percentage (as a percent)	6.30%
2.2% Canadian Maturing 2017
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 373	432
Debt instrument, stated interest rate percentage (as a percent)	2.20%
10.9% Other maturing in 2015-2020
Debt Disclosure
Aggregate carrying amount of long-term borrowings before adjusting for unamortized discount and fair value adjustment	$ 176	$ 367
Debt instrument, stated interest rate percentage (as a percent)	10.90%