Consolidating Financial Information - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	$ (154)	$ 290
Cash Flows from Investing Activities:
Capital Expenditures	(683)	(711)
Asset Dispositions	9	13
Short Term Securities Acquired	(51)	(46)
Short Term Securities Redeemed	51	34
Capital Contributions and Loans Incurred	0	0
Capital Redemptions and Loans Paid	0	0
Other Transactions	(1)	2
Total Cash Flows from Investing Activities	(675)	(708)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	544	219
Short Term Debt and Overdrafts Paid	(523)	(99)
Long Term Debt Incurred	4,972	4,129
Long Term Debt Paid	(4,193)	(4,025)
Common Stock Issued	12	9
Common Stock Repurchased	(205)	(200)
Common Stock Dividends Paid	(75)	(56)
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	(6)	(9)
Debt Related Costs and Other Transactions	(69)	(77)
Total Cash Flows from Financing Activities	457	(109)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	51	25
Net Change in Cash, Cash Equivalents and Restricted Cash	(321)	(502)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	1,189	1,502
Cash, Cash Equivalents and Restricted Cash at End of the Period	868	1,000
Reportable Legal Entities | Parent Company
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	179	31
Cash Flows from Investing Activities:
Capital Expenditures	(247)	(271)
Asset Dispositions	1	11
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	(75)	(165)
Capital Redemptions and Loans Paid	21	48
Other Transactions	0	0
Total Cash Flows from Investing Activities	(300)	(377)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	175	0
Short Term Debt and Overdrafts Paid	(145)	0
Long Term Debt Incurred	2,597	2,339
Long Term Debt Paid	(2,310)	(2,034)
Common Stock Issued	12	9
Common Stock Repurchased	(205)	(200)
Common Stock Dividends Paid	(75)	(56)
Capital Contributions and Loans Incurred	41	248
Capital Redemptions and Loans Paid	(61)	(148)
Intercompany Dividends Paid	0	0
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	(38)	(66)
Total Cash Flows from Financing Activities	(9)	92
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	0	0
Net Change in Cash, Cash Equivalents and Restricted Cash	(130)	(254)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	210	361
Cash, Cash Equivalents and Restricted Cash at End of the Period	80	107
Reportable Legal Entities | Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	0	26
Cash Flows from Investing Activities:
Capital Expenditures	(115)	(69)
Asset Dispositions	0	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
Other Transactions	0	0
Total Cash Flows from Investing Activities	(115)	(69)
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	52	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	62	59
Capital Redemptions and Loans Paid	(21)	(25)
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	93	34
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	3	1
Net Change in Cash, Cash Equivalents and Restricted Cash	(19)	(8)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	55	67
Cash, Cash Equivalents and Restricted Cash at End of the Period	36	59
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(303)	261
Cash Flows from Investing Activities:
Capital Expenditures	(323)	(375)
Asset Dispositions	8	2
Short Term Securities Acquired	(51)	(46)
Short Term Securities Redeemed	51	34
Capital Contributions and Loans Incurred	(41)	(248)
Capital Redemptions and Loans Paid	61	148
Other Transactions	(1)	2
Total Cash Flows from Investing Activities	(296)	(483)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	369	219
Short Term Debt and Overdrafts Paid	(378)	(99)
Long Term Debt Incurred	2,323	1,790
Long Term Debt Paid	(1,883)	(1,991)
Common Stock Issued	0	0
Common Stock Repurchased	0	0
Common Stock Dividends Paid	0	0
Capital Contributions and Loans Incurred	13	106
Capital Redemptions and Loans Paid	0	(23)
Intercompany Dividends Paid	(28)	(24)
Transactions with Minority Interests in Subsidiaries	(6)	(9)
Debt Related Costs and Other Transactions	(31)	(11)
Total Cash Flows from Financing Activities	379	(42)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	48	24
Net Change in Cash, Cash Equivalents and Restricted Cash	(172)	(240)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	924	1,074
Cash, Cash Equivalents and Restricted Cash at End of the Period	752	834
Consolidating Entries and Eliminations
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(30)	(28)
Cash Flows from Investing Activities:
Capital Expenditures	2	4
Asset Dispositions	0	0
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	116	413
Capital Redemptions and Loans Paid	(82)	(196)
Other Transactions	0	0
Total Cash Flows from Investing Activities	36	221
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	(116)	(413)
Capital Redemptions and Loans Paid	82	196
Intercompany Dividends Paid	28	24
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	0	0
Total Cash Flows from Financing Activities	(6)	(193)
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