Consolidating Financial Information - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	$ (185)	$ (67)
Cash Flows from Investing Activities:
Capital Expenditures	(497)	(466)
Asset Dispositions	2	1
Short Term Securities Acquired	(43)	(34)
Short Term Securities Redeemed	43	23
Capital Contributions and Loans Incurred	0	0
Capital Redemptions and Loans Paid	0	0
Other Transactions	(3)	0
Total Cash Flows from Investing Activities	(498)	(476)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	290	124
Short Term Debt and Overdrafts Paid	(303)	(36)
Long Term Debt Incurred	3,456	3,283
Long Term Debt Paid	(2,905)	(2,931)
Common Stock Issued	11	3
Common Stock Repurchased	(30)	(150)
Common Stock Dividends Paid	(50)	(38)
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	(5)	(7)
Debt Related Costs and Other Transactions	(38)	(76)
Total Cash Flows from Financing Activities	426	172
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	37	22
Net Change in Cash, Cash Equivalents and Restricted Cash	(220)	(349)
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	969	1,153
Reportable Legal Entities | Parent Company
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(49)	(199)
Cash Flows from Investing Activities:
Capital Expenditures	(190)	(189)
Asset Dispositions	1	0
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	(62)	(93)
Capital Redemptions and Loans Paid	0	25
Other Transactions	0
Total Cash Flows from Investing Activities	(251)	(257)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	40	0
Short Term Debt and Overdrafts Paid	(40)	0
Long Term Debt Incurred	2,090	2,051
Long Term Debt Paid	(1,759)	(1,523)
Common Stock Issued	11	3
Common Stock Repurchased	(30)	(150)
Common Stock Dividends Paid	(50)	(38)
Capital Contributions and Loans Incurred	30	243
Capital Redemptions and Loans Paid	(61)	(143)
Intercompany Dividends Paid	0	0
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	(26)	(66)
Total Cash Flows from Financing Activities	205	377
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	0	0
Net Change in Cash, Cash Equivalents and Restricted Cash	(95)	(79)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	210	361
Cash, Cash Equivalents and Restricted Cash at End of the Period	115	282
Reportable Legal Entities | Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(30)	(11)
Cash Flows from Investing Activities:
Capital Expenditures	(86)	(40)
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
Total Cash Flows from Investing Activities	(86)	(40)
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	0	(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	114	34
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	2	2
Net Change in Cash, Cash Equivalents and Restricted Cash	0	(15)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	55	67
Cash, Cash Equivalents and Restricted Cash at End of the Period	55	52
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(90)	160
Cash Flows from Investing Activities:
Capital Expenditures	(224)	(239)
Asset Dispositions	1	1
Short Term Securities Acquired	(43)	(34)
Short Term Securities Redeemed	43	23
Capital Contributions and Loans Incurred	(30)	(243)
Capital Redemptions and Loans Paid	61	143
Other Transactions	(3)
Total Cash Flows from Investing Activities	(195)	(349)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	250	124
Short Term Debt and Overdrafts Paid	(263)	(36)
Long Term Debt Incurred	1,314	1,232
Long Term Debt Paid	(1,146)	(1,408)
Common Stock Issued	0	0
Common Stock Repurchased	0	0
Common Stock Dividends Paid	0	0
Capital Contributions and Loans Incurred	0	34
Capital Redemptions and Loans Paid	0	0
Intercompany Dividends Paid	(13)	(15)
Transactions with Minority Interests in Subsidiaries	(5)	(7)
Debt Related Costs and Other Transactions	(12)	(10)
Total Cash Flows from Financing Activities	125	(86)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	35	20
Net Change in Cash, Cash Equivalents and Restricted Cash	(125)	(255)
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	799	819
Consolidating Entries and Eliminations
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(16)	(17)
Cash Flows from Investing Activities:
Capital Expenditures	3	2
Asset Dispositions	0	0
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	92	336
Capital Redemptions and Loans Paid	(61)	(168)
Other Transactions	0
Total Cash Flows from Investing Activities	34	170
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	(92)	(336)
Capital Redemptions and Loans Paid	61	168
Intercompany Dividends Paid	13	15
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	0	0
Total Cash Flows from Financing Activities	(18)	(153)
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