Condensed Consolidating Financial Information of Guarantor Subsidiaries - CONDENSED CONSOLIDATING CASH FLOW INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ 2,230	$ 1,953	$ 1,995
Net cash used in investing activities	(3,705)	(859)	(1,170)
Net cash provided by (used in) financing activities	1,497	(964)	(775)
Effect of foreign exchange rates	18	3	(29)
Net increase in cash and cash equivalents	40	133	21
Cash and cash equivalents at beginning of year	312	179	158
Cash and cash equivalents at end of year	352	312	179
Eliminations
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	0	0	0
Net cash used in investing activities	0	0	0
Net cash provided by (used in) financing activities	0	0	0
Effect of foreign exchange rates	0	0	0
Net increase in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	0	0	0
Parent \| Reportable Legal Entities
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	21	9	13
Net cash used in investing activities	(21)	(9)	(13)
Net cash provided by (used in) financing activities	0	0	0
Effect of foreign exchange rates	0	0	0
Net increase in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	0	0	0
URNA \| Reportable Legal Entities
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	2,312	1,774	1,804
Net cash used in investing activities	(3,575)	(844)	(1,035)
Net cash provided by (used in) financing activities	1,265	(927)	(759)
Effect of foreign exchange rates	0	0	0
Net increase in cash and cash equivalents	2	3	10
Cash and cash equivalents at beginning of year	21	18	8
Cash and cash equivalents at end of year	23	21	18
Guarantor Subsidiaries \| Reportable Legal Entities
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(3)	(3)	(3)
Net cash used in investing activities	0	0	0
Net cash provided by (used in) financing activities	3	3	3
Effect of foreign exchange rates	0	0	0
Net increase in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	0	0	0
Foreign \| Reportable Legal Entities
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	132	136	170
Net cash used in investing activities	(109)	(6)	(122)
Net cash provided by (used in) financing activities	(3)	(3)	(8)
Effect of foreign exchange rates	18	3	(29)
Net increase in cash and cash equivalents	38	130	11
Cash and cash equivalents at beginning of year	291	161	150
Cash and cash equivalents at end of year	329	291	161
SPV \| Reportable Legal Entities
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(232)	37	11
Net cash used in investing activities	0	0	0
Net cash provided by (used in) financing activities	232	(37)	(11)
Effect of foreign exchange rates	0	0	0
Net increase in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of year	0	0	0
Cash and cash equivalents at end of year	$ 0	$ 0	$ 0

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
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-Name Accounting Standards Codification
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Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes.

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Amount of increase (decrease) from the effect of exchange rate changes on cash and cash equivalent balances held in foreign currencies.

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Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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