Income Taxes - Deferred Tax Asset Valuation Allowances (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Valuation Allowance [Line Items]
Other amortizable assets	$ 385	$ 394
Tax credits	564
NOLs - Non-U.S.	65
Other carryforwards	19
NOLs - State	17
Total deferred tax assets	1,591	1,455
Valuation Allowance	(295)	$ (330)
Other amortizable assets
Valuation Allowance [Line Items]
Valuation Allowance	(233)
Tax credits
Valuation Allowance [Line Items]
Valuation Allowance	0
NOLs - Non-U.S.
Valuation Allowance [Line Items]
Valuation Allowance	(40)
Other carryforwards
Valuation Allowance [Line Items]
Valuation Allowance	(5)
NOLs - State
Valuation Allowance [Line Items]
Valuation Allowance	$ (17)

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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