Long-Term Debt - Long Term Debt Maturities Schedule (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Debt Disclosure [Abstract]
2014	$ 3,939	[1]
2015	5,681
2016	5,462
2017	1,751
2018	295
Thereafter	3,711
Total	$ 20,839		$ 28,426
Weighted average interest rate on debt maturing in next twelve months	2.285%

[1] Weighted average interest rate on long-term debt maturing in 2014 is 2.285 percent.