Accumulated Other Comprehensive Income (AOCI) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	$ (2,141)	$ (2,598)
Other comprehensive income (loss) before reclassifications	369	768
Amounts reclassified from AOCI	29	64
Other comprehensive income (loss), tax, portion attributable to parent	(100)	(77)
Other Comprehensive Income (Loss), Net of Tax	298	755
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(1,843)	(1,843)
Foreign Currency Translation Adjustment [Member]
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	(1,684)	(2,102)
Other comprehensive income (loss) before reclassifications	244	626
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss), tax, portion attributable to parent	(40)	(4)
Other Comprehensive Income (Loss), Net of Tax	204	622
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(1,480)	(1,480)
Deferred Gain (Loss) On Hedging Activities [Member]
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	39	6
Other comprehensive income (loss) before reclassifications	(41)	(10)
Amounts reclassified from AOCI	15	22
Other comprehensive income (loss), tax, portion attributable to parent	6	1
Other Comprehensive Income (Loss), Net of Tax	(20)	13
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	19	19
Pension Liability Adjustment [Member]
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	(510)	(521)
Other comprehensive income (loss) before reclassifications	160	151
Amounts reclassified from AOCI	14	42
Other comprehensive income (loss), tax, portion attributable to parent	(66)	(74)
Other Comprehensive Income (Loss), Net of Tax	108	119
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(402)	(402)
Unrealized Gain (Loss) On Investments [Member]
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	14	19
Other comprehensive income (loss) before reclassifications	6	1
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss), tax, portion attributable to parent	0	0
Other Comprehensive Income (Loss), Net of Tax	6	1
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	$ 20	$ 20