Accumulated Other Comprehensive Income (AOCI) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	$ (2,574)	$ (2,598)
Other comprehensive income (loss) before reclassifications	386	399
Amounts reclassified from AOCI	18	35
Other comprehensive income (loss), tax, portion attributable to parent	29	23
Other Comprehensive Income (Loss), Net of Tax	433	457
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(2,141)	(2,141)
Foreign Currency Translation Adjustment [Member]
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	(2,078)	(2,102)
Other comprehensive income (loss) before reclassifications	361	382
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss), tax, portion attributable to parent	33	36
Other Comprehensive Income (Loss), Net of Tax	394	418
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(1,684)	(1,684)
Deferred Gain (Loss) On Hedging Activities [Member]
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	6	6
Other comprehensive income (loss) before reclassifications	30	31
Amounts reclassified from AOCI	5	7
Other comprehensive income (loss), tax, portion attributable to parent	(2)	(5)
Other Comprehensive Income (Loss), Net of Tax	33	33
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	39	39
Pension Liability Adjustment [Member]
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	(515)	(521)
Other comprehensive income (loss) before reclassifications	(6)	(9)
Amounts reclassified from AOCI	13	28
Other comprehensive income (loss), tax, portion attributable to parent	(2)	(8)
Other Comprehensive Income (Loss), Net of Tax	5	11
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(510)	(510)
Unrealized Gain (Loss) On Investments [Member]
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	13	19
Other comprehensive income (loss) before reclassifications	1	(5)
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss), tax, portion attributable to parent	0	0
Other Comprehensive Income (Loss), Net of Tax	1	(5)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	$ 14	$ 14