Accumulated Other Comprehensive Income (Loss) (After-tax Changes by Component) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	$ (2,274)	$ (1,565)
Amounts arising during the period	(56)	90
Reclassifications from accumulated other comprehensive income	19	46
Net other comprehensive income during the period	(37)	136
Balance at end of period	(2,311)	(1,429)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(286)	(11)
Amounts arising during the period	(66)	131
Reclassifications from accumulated other comprehensive income	0	0
Net other comprehensive income during the period	(66)	131
Balance at end of period	(352)	120
Available For Sale Securities Unrealized Gains (Losses) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	202	173
Amounts arising during the period	5	5
Reclassifications from accumulated other comprehensive income	(1)	(1)
Net other comprehensive income during the period	4	4
Balance at end of period	206	177
Qualifying Derivatives Unrealized Gains (Losses) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	20	94
Amounts arising during the period	6	(46)
Reclassifications from accumulated other comprehensive income	(17)	19
Net other comprehensive income during the period	(11)	(27)
Balance at end of period	9	67
Equity Investees Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	1	1
Amounts arising during the period	0	0
Reclassifications from accumulated other comprehensive income	(1)	0
Net other comprehensive income during the period	(1)	0
Balance at end of period	0	1
Defined Benefit Plans Prior Service Costs [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	3	(6)
Amounts arising during the period	0	0
Reclassifications from accumulated other comprehensive income	0	1
Net other comprehensive income during the period	0	1
Balance at end of period	3	(5)
Defined Benefit Plans Actuarial Gain (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(2,215)	(1,817)
Amounts arising during the period	(1)	0
Reclassifications from accumulated other comprehensive income	38	27
Net other comprehensive income during the period	37	27
Balance at end of period	(2,178)	(1,790)
Defined Benefit Plans Transition Assset Obligation [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	1	1
Amounts arising during the period	0	0
Reclassifications from accumulated other comprehensive income	0	0
Net other comprehensive income during the period	0	0
Balance at end of period	$ 1	$ 1