Long-Term Debt (Scheduled Remaining Maturity Of Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
2013	$ 4,963
2014	17,335
2015	13,375
2016	5,866
2017	6,102
2018 and thereafter	16,201
Derivative, Amount of Hedged Item	692	1,094
Long-term debt	64,534	74,561
Unsecured Debt [Member]
Debt Instrument [Line Items]
2013	759
2014	5,400
2015	5,067
2016	1,907
2017	3,612
2018 and thereafter	15,498
Derivative, Amount of Hedged Item	692	1,094
Long-term debt	32,935	33,650
Unsecured Debt [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
2013	896
2014	5,588
2015	5,123
2016	1,970
2017	3,687
2018 and thereafter	16,695
Derivative, Amount of Hedged Item	692
Long-term debt	34,651
Unsecured Debt [Member] | Original Issue Discount [Member]
Debt Instrument [Line Items]
2013	(137)
2014	(188)
2015	(56)
2016	(63)
2017	(75)
2018 and thereafter	(1,197)
Derivative, Amount of Hedged Item	0
Long-term debt	(1,716)
Secured Debt [Member]
Debt Instrument [Line Items]
Derivative, Amount of Hedged Item	0	0
Long-term debt	31,599	40,911
Secured Debt [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
2013	4,204
2014	11,935
2015	8,308
2016	3,959
2017	2,490
2018 and thereafter	703
Derivative, Amount of Hedged Item	0
Long-term debt	$ 31,599