Consolidating Financial Information - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	$ (291)	$ (84)
Cash Flows from Investing Activities:
Capital Expenditures	(401)	(442)
Asset Dispositions	2	2
Short Term Securities Acquired	(67)	(30)
Short Term Securities Redeemed	67	38
Capital Contributions and Loans Incurred	0	0
Capital Redemptions and Loans Paid	0	0
Notes Receivable	(7)	0
Other Transactions	(13)	(38)
Total Cash Flows from Investing Activities	(419)	(470)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	983	1,012
Short Term Debt and Overdrafts Paid	(908)	(920)
Long Term Debt Incurred	3,479	3,544
Long Term Debt Paid	(2,628)	(2,933)
Common Stock Issued	1	3
Common Stock Repurchased	0	(100)
Common Stock Dividends Paid	(74)	(67)
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	(25)	(26)
Debt Related Costs and Other Transactions	(17)	6
Total Cash Flows from Financing Activities	811	519
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	6	(25)
Net Change in Cash, Cash Equivalents and Restricted Cash	107	(60)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	873	1,110
Cash, Cash Equivalents and Restricted Cash at End of the Period	980	1,050
Reportable Legal Entities | Parent Company
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(77)	457
Cash Flows from Investing Activities:
Capital Expenditures	(153)	(180)
Asset Dispositions	0	0
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	(223)	(306)
Capital Redemptions and Loans Paid	169	69
Notes Receivable	(7)	0
Other Transactions	0	(38)
Total Cash Flows from Investing Activities	(214)	(455)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	355	575
Short Term Debt and Overdrafts Paid	(355)	(575)
Long Term Debt Incurred	1,781	1,605
Long Term Debt Paid	(1,302)	(1,267)
Common Stock Issued	1	3
Common Stock Repurchased	0	(100)
Common Stock Dividends Paid	(74)	(67)
Capital Contributions and Loans Incurred	0	213
Capital Redemptions and Loans Paid	0	(430)
Intercompany Dividends Paid	0	0
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	1	7
Total Cash Flows from Financing Activities	407	(36)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	0	0
Net Change in Cash, Cash Equivalents and Restricted Cash	116	(34)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	168	201
Cash, Cash Equivalents and Restricted Cash at End of the Period	284	167
Reportable Legal Entities | Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(19)	(9)
Cash Flows from Investing Activities:
Capital Expenditures	(20)	(41)
Asset Dispositions	0	2
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	0
Other Transactions	0	0
Total Cash Flows from Investing Activities	(20)	(39)
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	15
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	49	52
Capital Redemptions and Loans Paid	0	0
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	49	67
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	2	(2)
Net Change in Cash, Cash Equivalents and Restricted Cash	12	17
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	30	32
Cash, Cash Equivalents and Restricted Cash at End of the Period	42	49
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(174)	(336)
Cash Flows from Investing Activities:
Capital Expenditures	(228)	(220)
Asset Dispositions	2	0
Short Term Securities Acquired	(67)	(30)
Short Term Securities Redeemed	67	38
Capital Contributions and Loans Incurred	0	(213)
Capital Redemptions and Loans Paid	0	430
Notes Receivable	0	0
Other Transactions	(13)	0
Total Cash Flows from Investing Activities	(239)	5
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	628	437
Short Term Debt and Overdrafts Paid	(553)	(345)
Long Term Debt Incurred	1,698	1,924
Long Term Debt Paid	(1,326)	(1,666)
Common Stock Issued	0	0
Common Stock Repurchased	0	0
Common Stock Dividends Paid	0	0
Capital Contributions and Loans Incurred	174	254
Capital Redemptions and Loans Paid	(169)	(69)
Intercompany Dividends Paid	(21)	(197)
Transactions with Minority Interests in Subsidiaries	(25)	(26)
Debt Related Costs and Other Transactions	(18)	(1)
Total Cash Flows from Financing Activities	388	311
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	4	(23)
Net Change in Cash, Cash Equivalents and Restricted Cash	(21)	(43)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	675	877
Cash, Cash Equivalents and Restricted Cash at End of the Period	654	834
Consolidating Entries and Eliminations
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(21)	(196)
Cash Flows from Investing Activities:
Capital Expenditures	0	(1)
Asset Dispositions	0	0
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	223	519
Capital Redemptions and Loans Paid	(169)	(499)
Notes Receivable	0	0
Other Transactions	0	0
Total Cash Flows from Investing Activities	54	19
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	(223)	(519)
Capital Redemptions and Loans Paid	169	499
Intercompany Dividends Paid	21	197
Transactions with Minority Interests in Subsidiaries	0	0
Debt Related Costs and Other Transactions	0	0
Total Cash Flows from Financing Activities	(33)	177
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