Income Taxes - Schedule of Expiration Periods of Deferred Tax Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	$ 3,267
Tax credit carryforwards	378
Other	460
Valuation allowance	(2,307)	$ (2,121)	$ (2,357)	$ (2,459)
Deferred tax assets, net	1,798	$ 1,618
Expires within 10 years
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	378
Tax credit carryforwards	299
Other	0
Valuation allowance	(644)
Deferred tax assets, net	33
Expires within 11-20 years
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	262
Tax credit carryforwards	66
Other	0
Valuation allowance	(161)
Deferred tax assets, net	167
No expiration
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	2,627
Tax credit carryforwards	13
Other	389
Valuation allowance	(1,479)
Deferred tax assets, net	1,550
Other
Tax Credit Carryforward [Line Items]
Tax loss carryforwards	0
Tax credit carryforwards	0
Other	71
Valuation allowance	(23)
Deferred tax assets, net	$ 48