Long-Term Debt (Scheduled Remaining Maturity Of Long-Term Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
2016	$ 6,923
2017	17,005
2018	12,050
2019	8,724
2020	6,235
2021 and thereafter	10,600
Derivative, Amount of Hedged Item	507	$ 331
Long-term debt	62,044	66,234
Unsecured Debt [Member]
Debt Instrument [Line Items]
2016	1,354
2017	4,284
2018	3,602
2019	1,596
2020	2,177
2021 and thereafter	7,096
Derivative, Amount of Hedged Item	497	334
Long-term debt	20,606	20,966
Unsecured Debt [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
2016	1,412
2017	4,371
2018	3,701
2019	1,631
2020	2,213
2021 and thereafter	8,156
Derivative, Amount of Hedged Item	497
Long-term debt	21,981
Unsecured Debt [Member] | Original Issue Discount [Member]
Debt Instrument [Line Items]
2016	(58)
2017	(87)
2018	(99)
2019	(35)
2020	(36)
2021 and thereafter	(1,060)
Derivative, Amount of Hedged Item	0
Long-term debt	(1,375)
Secured Debt [Member]
Debt Instrument [Line Items]
Derivative, Amount of Hedged Item	10	(3)
Long-term debt	41,438	$ 45,268
Secured Debt [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
2016	5,569
2017	12,721
2018	8,448
2019	7,128
2020	4,058
2021 and thereafter	3,504
Derivative, Amount of Hedged Item	10
Long-term debt	$ 41,438