Basis of Presentation and Significant Accounting Policies - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 3,970	$ 4,010	$ 3,038	$ 3,061
Other comprehensive (loss) income	(197)	275	(141)
Balance at end of period	3,970	4,010	3,038
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(143)	(43)	(206)
Other comprehensive income	(96)	180
Amounts reclassified from AOCI	(4)	0
Impact of tax reform act		(17)
Other comprehensive (loss) income	(100)	180
Balance at end of period	(143)	(43)	(206)
Derivative Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	1	7	0
Other comprehensive income	12	10
Amounts reclassified from AOCI	(18)	(5)
Impact of tax reform act		2
Other comprehensive (loss) income	(6)	5
Balance at end of period	1	7	0
Defined Benefit Plans Liability
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(12)	79	(13)
Other comprehensive income	(89)	92
Amounts reclassified from AOCI	(2)	(2)
Impact of tax reform act		2
Other comprehensive (loss) income	(91)	90
Balance at end of period	(12)	79	(13)
Less: AOCI Attributable to Noncontrolling Interests
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	0	(27)	25
Other comprehensive income	27	(52)
Amounts reclassified from AOCI	0	0
Impact of tax reform act		0
Other comprehensive (loss) income	27	(52)
Balance at end of period	0	(27)	25
AOCI Attributable to the Company
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(154)	16	(194)	$ (72)
Other comprehensive income	(146)	230
Amounts reclassified from AOCI	(24)	(7)
Impact of tax reform act		(13)
Other comprehensive (loss) income	(170)	223	(122)
Balance at end of period	$ (154)	$ 16	$ (194)