Summary of Accounting Policies - Error Correction, Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	$ (105)	$ 74
Foreign currency translation adjustments	35	27
Defined benefit plans	1	3
Other comprehensive income (loss) — net of tax	40	30
Comprehensive income (loss)	(65)	104
Less: Comprehensive income (loss) attributable to noncontrolling interests	18	22
Comprehensive income (loss) attributable to common shareholders	$ (83)	82
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income		72
Foreign currency translation adjustments		27
Defined benefit plans		3
Other comprehensive income (loss) — net of tax		30
Comprehensive income (loss)		102
Less: Comprehensive income (loss) attributable to noncontrolling interests		22
Comprehensive income (loss) attributable to common shareholders		80
Reclasses
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income		0
Foreign currency translation adjustments		0
Defined benefit plans		0
Other comprehensive income (loss) — net of tax		0
Comprehensive income (loss)		0
Less: Comprehensive income (loss) attributable to noncontrolling interests		0
Comprehensive income (loss) attributable to common shareholders		0
As Reclassified
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income		72
Foreign currency translation adjustments		27
Defined benefit plans		3
Other comprehensive income (loss) — net of tax		30
Comprehensive income (loss)		102
Less: Comprehensive income (loss) attributable to noncontrolling interests		22
Comprehensive income (loss) attributable to common shareholders		80
Revisions
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income		2
Foreign currency translation adjustments		0
Defined benefit plans		0
Other comprehensive income (loss) — net of tax		0
Comprehensive income (loss)		2
Less: Comprehensive income (loss) attributable to noncontrolling interests		0
Comprehensive income (loss) attributable to common shareholders		$ 2