Long-Term Debt (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Total debt at par value	$ 10,902	$ 11,228
Unamortized discount, net	(339)	(383)
Net carrying amount	10,563	10,845
Fair Value	$ 11,300	$ 11,600