Consolidating Financial Information - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	$ (24)	$ (154)
Cash Flows from Investing Activities:
Capital Expenditures	(615)	(683)
Asset Dispositions	2	9
Short Term Securities Acquired	(61)	(51)
Short Term Securities Redeemed	61	51
Capital Contributions and Loans Incurred	0	0
Capital Redemptions and Loans Paid	0	0
Notes Receivable	(50)	0
Other Transactions	(1)	(1)
Total Cash Flows from Investing Activities	(664)	(675)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	1,458	544
Short Term Debt and Overdrafts Paid	(1,267)	(523)
Long Term Debt Incurred	4,704	4,972
Long Term Debt Paid	(3,992)	(4,193)
Common Stock Issued	4	12
Common Stock Repurchased	(200)	(205)
Common Stock Dividends Paid	(100)	(75)
Capital Contributions and Loans Incurred	0	0
Capital Redemptions and Loans Paid	0	0
Intercompany Dividends Paid	0	0
Transactions with Minority Interests in Subsidiaries	(27)	(6)
Debt Related Costs and Other Transactions	(3)	(69)
Total Cash Flows from Financing Activities	577	457
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	(37)	51
Net Change in Cash, Cash Equivalents and Restricted Cash	(148)	(321)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	1,110	1,189
Cash, Cash Equivalents and Restricted Cash at End of the Period	962	868
Reportable Legal Entities | Parent Company
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	815	179
Cash Flows from Investing Activities:
Capital Expenditures	(248)	(247)
Asset Dispositions	0	1
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	(597)	(75)
Capital Redemptions and Loans Paid	193	21
Notes Receivable	(50)
Other Transactions	3	0
Total Cash Flows from Investing Activities	(699)	(300)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	800	175
Short Term Debt and Overdrafts Paid	(775)	(145)
Long Term Debt Incurred	2,305	2,597
Long Term Debt Paid	(1,982)	(2,310)
Common Stock Issued	4	12
Common Stock Repurchased	(200)	(205)
Common Stock Dividends Paid	(100)	(75)
Capital Contributions and Loans Incurred	213	41
Capital Redemptions and Loans Paid	(430)	(61)
Intercompany Dividends Paid	0	0
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	16	(38)
Total Cash Flows from Financing Activities	(149)	(9)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	0	0
Net Change in Cash, Cash Equivalents and Restricted Cash	(33)	(130)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	201	210
Cash, Cash Equivalents and Restricted Cash at End of the Period	168	80
Reportable Legal Entities | Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(5)	0
Cash Flows from Investing Activities:
Capital Expenditures	(55)	(115)
Asset Dispositions	2	0
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	0	0
Capital Redemptions and Loans Paid	0	0
Notes Receivable	0
Other Transactions	0	0
Total Cash Flows from Investing Activities	(53)	(115)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	0	0
Short Term Debt and Overdrafts Paid	0	0
Long Term Debt Incurred	15	52
Long Term Debt Paid	0	0
Common Stock Issued	0	0
Common Stock Repurchased	0	0
Common Stock Dividends Paid	0	0
Capital Contributions and Loans Incurred	52	62
Capital Redemptions and Loans Paid	(14)	(21)
Intercompany Dividends Paid	0	0
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	0	0
Total Cash Flows from Financing Activities	53	93
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	(1)	3
Net Change in Cash, Cash Equivalents and Restricted Cash	(6)	(19)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	32	55
Cash, Cash Equivalents and Restricted Cash at End of the Period	26	36
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(295)	(303)
Cash Flows from Investing Activities:
Capital Expenditures	(311)	(323)
Asset Dispositions	0	8
Short Term Securities Acquired	(61)	(51)
Short Term Securities Redeemed	61	51
Capital Contributions and Loans Incurred	(213)	(41)
Capital Redemptions and Loans Paid	430	61
Notes Receivable	0
Other Transactions	(4)	(1)
Total Cash Flows from Investing Activities	(98)	(296)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	658	369
Short Term Debt and Overdrafts Paid	(492)	(378)
Long Term Debt Incurred	2,384	2,323
Long Term Debt Paid	(2,010)	(1,883)
Common Stock Issued	0	0
Common Stock Repurchased	0	0
Common Stock Dividends Paid	0	0
Capital Contributions and Loans Incurred	545	13
Capital Redemptions and Loans Paid	(179)	0
Intercompany Dividends Paid	(540)	(28)
Transactions with Minority Interests in Subsidiaries	(27)	(6)
Debt Related Costs and Other Transactions	(19)	(31)
Total Cash Flows from Financing Activities	320	379
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	(36)	48
Net Change in Cash, Cash Equivalents and Restricted Cash	(109)	(172)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	877	924
Cash, Cash Equivalents and Restricted Cash at End of the Period	768	752
Consolidating Entries and Eliminations
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(539)	(30)
Cash Flows from Investing Activities:
Capital Expenditures	(1)	2
Asset Dispositions	0	0
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	810	116
Capital Redemptions and Loans Paid	(623)	(82)
Notes Receivable	0
Other Transactions	0	0
Total Cash Flows from Investing Activities	186	36
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	0	0
Short Term Debt and Overdrafts Paid	0	0
Long Term Debt Incurred	0	0
Long Term Debt Paid	0	0
Common Stock Issued	0	0
Common Stock Repurchased	0	0
Common Stock Dividends Paid	0	0
Capital Contributions and Loans Incurred	(810)	(116)
Capital Redemptions and Loans Paid	623	82
Intercompany Dividends Paid	540	28
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	0	0
Total Cash Flows from Financing Activities	353	(6)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	0	0
Net Change in Cash, Cash Equivalents and Restricted Cash	0	0
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	0	0
Cash, Cash Equivalents and Restricted Cash at End of the Period	$ 0	$ 0