Debt Financing Arrangements (Long-Term Debt) (Details) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2017 EUR (€)	Sep. 29, 2017	Sep. 14, 2017 USD ($)	Apr. 15, 2017 USD ($)	Aug. 11, 2016 USD ($)
Debt Instruments [Line Items]
Long-term Debt	$ 6,636	$ 6,777
Current maturities	(13)	(273)
Total long-term debt	6,623	6,504
Notes One Point Seventy Five Percent Due In Two Thousand Twenty-Three [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 714	627
Debt Instrument, Face Amount | €			€ 600
Debt Instrument, Interest Rate, Stated Percentage	1.75%		1.75%
Debt instrument, maturity year	2023
Notes Two Point Five Percent Due in Two Thousand Twenty-Six [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 992	991
Debt Instrument, Face Amount	$ 1,000						$ 1,000
Debt Instrument, Interest Rate, Stated Percentage	2.50%		2.50%				2.50%
Debt instrument, maturity year	2026
Floating Rate Notes Due In Two Thousand Nineteen [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 599	526
Debt Instrument, Face Amount | €			€ 500
Debt instrument, maturity year	2019
Debentures four point four seven nine percent due in two thousand twenty one [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 501	510
Debt Instrument, Face Amount	$ 516
Debt Instrument, Interest Rate, Stated Percentage	4.479%		4.479%
Debt instrument, maturity year	2021
Notes Three Point Seventy-Five Percent Due in Two Thousand Forty-Seven [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 492	0
Debt Instrument, Face Amount	$ 500				$ 500
Debt Instrument, Interest Rate, Stated Percentage	3.75%		3.75%		3.75%
Debt instrument, maturity year	2047
Debentures five point three seven five percent due in two thousand thirty five [Member}
Debt Instruments [Line Items]
Long-term Debt	$ 460	459
Debt Instrument, Face Amount	$ 470
Debt Instrument, Interest Rate, Stated Percentage	5.375%		5.375%
Debt instrument, maturity year	2035
Debentures five point seven six five percent due in two thousand forty one [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 378	378
Debt Instrument, Face Amount	$ 378
Debt Instrument, Interest Rate, Stated Percentage	5.765%		5.765%
Debt instrument, maturity year	2041
Debentures five point nine three five percent due in two thousand thirty two [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 378	378
Debt Instrument, Face Amount	$ 383
Debt Instrument, Interest Rate, Stated Percentage	5.935%		5.935%
Debt instrument, maturity year	2032
Debentures four point zero one six percent due in two thousand forty three [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 383	380
Debt Instrument, Face Amount	$ 570
Debt Instrument, Interest Rate, Stated Percentage	4.016%		4.016%
Debt instrument, maturity year	2043
Debentures four point five three five percent due in two thousand forty two [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 379	377
Debt Instrument, Face Amount	$ 528
Debt Instrument, Interest Rate, Stated Percentage	4.535%		4.535%
Debt instrument, maturity year	2042
Debentures eight point three seven five percent due in two thousand seventeen [ Member]
Debt Instruments [Line Items]
Long-term Debt	$ 0	260
Debt Instrument, Face Amount		$ 261				$ 261
Debt Instrument, Interest Rate, Stated Percentage		8.375%				8.375%
Debt instrument, maturity year		2017
Debentures seven percent due in two thousand thirty one [Member]
Debt Instruments [Line Items]
Long-term Debt	163	$ 163
Debt Instrument, Face Amount	$ 164
Debt Instrument, Interest Rate, Stated Percentage	7.00%		7.00%
Debt instrument, maturity year	2031
Debentures six point six two five percent due in two thousand twenty nine [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 159	159
Debt Instrument, Face Amount	$ 160
Debt Instrument, Interest Rate, Stated Percentage	6.625%		6.625%
Debt instrument, maturity year	2029
Debentures six point ninety-five due in two thousand ninety seven [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 155	155
Debt Instrument, Face Amount	$ 159
Debt Instrument, Interest Rate, Stated Percentage	6.95%		6.95%
Debt instrument, maturity year	2097
Debentures seven point five percent due in two thousand twenty seven [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 150	149
Debt Instrument, Face Amount	$ 150
Debt Instrument, Interest Rate, Stated Percentage	7.50%		7.50%
Debt instrument, maturity year	2027
Debentures six point forty-five percent due in two thousand thirty eight [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 126	125
Debt Instrument, Face Amount	$ 127
Debt Instrument, Interest Rate, Stated Percentage	6.45%		6.45%
Debt instrument, maturity year	2038
Debentures six point seventy-five percent due in two thousand twenty seven [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 117	117
Debt Instrument, Face Amount	$ 118
Debt Instrument, Interest Rate, Stated Percentage	6.75%		6.75%
Debt instrument, maturity year	2027
Notes Five Point Forty-Five Percent Due In Two Thousand Eighteen [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 0	560
Debt Instrument, Face Amount		$ 559
Debt Instrument, Interest Rate, Stated Percentage		5.45%		5.45%
Debt instrument, maturity year		2018
Other [Member]
Debt Instruments [Line Items]
Long-term Debt	$ 490	$ 463