Consolidating Financial Information - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	$ (389)	$ (286)
Cash Flows from Investing Activities:
Capital Expenditures	(248)	(271)
Asset Dispositions	0	1
Short Term Securities Acquired	(8)	(11)
Short Term Securities Redeemed	8	11
Capital Contributions and Loans Incurred	0	0
Capital Redemptions and Loans Paid	0	0
Total Cash Flows from Investing Activities	(248)	(270)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	584	51
Short Term Debt and Overdrafts Paid	(518)	(82)
Long Term Debt Incurred	1,652	1,838
Long Term Debt Paid	(1,226)	(1,369)
Common Stock Issued	1	9
Common Stock Repurchased	(25)	(25)
Common Stock Dividends Paid	(34)	(25)
Capital Contributions and Loans Incurred	0	0
Capital Redemptions and Loans Paid	0	0
Intercompany Dividends Paid		0
Transactions with Minority Interests in Subsidiaries	(22)	0
Debt Related Costs and Other Transactions	(13)	1
Total Cash Flows from Financing Activities	399	398
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	16	20
Net Change in Cash, Cash Equivalents and Restricted Cash	(222)	(138)
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	888	1,051
Reportable Legal Entities | Parent Company
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	266	(81)
Cash Flows from Investing Activities:
Capital Expenditures	(101)	(113)
Asset Dispositions		1
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	(91)	(23)
Capital Redemptions and Loans Paid	38	0
Total Cash Flows from Investing Activities	(154)	(135)
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	325	0
Short Term Debt and Overdrafts Paid	(325)	0
Long Term Debt Incurred	705	1,270
Long Term Debt Paid	(541)	(655)
Common Stock Issued	1	9
Common Stock Repurchased	(25)	(25)
Common Stock Dividends Paid	(34)	(25)
Capital Contributions and Loans Incurred	91	30
Capital Redemptions and Loans Paid	(360)	(448)
Intercompany Dividends Paid		0
Transactions with Minority Interests in Subsidiaries	0
Debt Related Costs and Other Transactions	7	12
Total Cash Flows from Financing Activities	(156)	168
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	0	0
Net Change in Cash, Cash Equivalents and Restricted Cash	(44)	(48)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	201	210
Cash, Cash Equivalents and Restricted Cash at End of the Period	157	162
Reportable Legal Entities | Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	0	(4)
Cash Flows from Investing Activities:
Capital Expenditures	(28)	(49)
Asset Dispositions		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
Total Cash Flows from Investing Activities	(28)	(49)
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	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	8	23
Capital Redemptions and Loans Paid	0	0
Intercompany Dividends Paid		0
Transactions with Minority Interests in Subsidiaries	0
Debt Related Costs and Other Transactions	0	0
Total Cash Flows from Financing Activities	23	23
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	(1)	0
Net Change in Cash, Cash Equivalents and Restricted Cash	(6)	(30)
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	25
Reportable Legal Entities | Non-Guarantor Subsidiaries
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	(656)	(191)
Cash Flows from Investing Activities:
Capital Expenditures	(118)	(109)
Asset Dispositions		0
Short Term Securities Acquired	(8)	(11)
Short Term Securities Redeemed	8	11
Capital Contributions and Loans Incurred	(91)	(30)
Capital Redemptions and Loans Paid	360	448
Total Cash Flows from Investing Activities	151	309
Cash Flows from Financing Activities:
Short Term Debt and Overdrafts Incurred	259	51
Short Term Debt and Overdrafts Paid	(193)	(82)
Long Term Debt Incurred	932	568
Long Term Debt Paid	(685)	(714)
Common Stock Issued	0	0
Common Stock Repurchased	0	0
Common Stock Dividends Paid	0	0
Capital Contributions and Loans Incurred	83	0
Capital Redemptions and Loans Paid	(38)	0
Intercompany Dividends Paid		(10)
Transactions with Minority Interests in Subsidiaries	(22)
Debt Related Costs and Other Transactions	(20)	(11)
Total Cash Flows from Financing Activities	316	(198)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	17	20
Net Change in Cash, Cash Equivalents and Restricted Cash	(172)	(60)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	877	924
Cash, Cash Equivalents and Restricted Cash at End of the Period	705	864
Consolidating Entries and Eliminations
Cash Flows from Operating Activities:
Total Cash Flows from Operating Activities	1	(10)
Cash Flows from Investing Activities:
Capital Expenditures	(1)	0
Asset Dispositions		0
Short Term Securities Acquired	0	0
Short Term Securities Redeemed	0	0
Capital Contributions and Loans Incurred	182	53
Capital Redemptions and Loans Paid	(398)	(448)
Total Cash Flows from Investing Activities	(217)	(395)
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	(182)	(53)
Capital Redemptions and Loans Paid	398	448
Intercompany Dividends Paid		10
Transactions with Minority Interests in Subsidiaries	0
Debt Related Costs and Other Transactions	0	0
Total Cash Flows from Financing Activities	216	405
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