Income Taxes - Schedule of Expiration Periods of Deferred Tax Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	$ 3,159
Tax credit carryforwards	579
Other	1,084
Valuation allowance	(2,486)	$ (2,584)	$ (1,940)	$ (1,291)
Deferred tax assets, net	2,336	$ 2,503
Expires within 10 years
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	300
Tax credit carryforwards	497
Other	0
Valuation allowance	(752)
Deferred tax assets, net	45
Expires within 11-20 years
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	461
Tax credit carryforwards	70
Other	0
Valuation allowance	(287)
Deferred tax assets, net	244
No expiration
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	2,398
Tax credit carryforwards	12
Other	64
Valuation allowance	(1,390)
Deferred tax assets, net	1,084
Other(2)
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	0
Tax credit carryforwards	0
Other	1,020
Valuation allowance	(57)
Deferred tax assets, net	$ 963