Annual report pursuant to Section 13 and 15(d)

Income Taxes - Narrative (Details)

v3.20.4
Income Taxes - Narrative (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
unit
Dec. 31, 2018
USD ($)
Operating Loss Carryforwards [Line Items]      
Income tax expense as a result of one-time discrete event $ 38    
Deferred Tax Assets, Valuation Allowance 190 $ 196  
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount 6    
Number Of Years In Cumulative Loss Position     3 years
Number Of Years In Cumulative Income Position   3 years  
Number of Long Term Agreements Commenced During The Year | unit   13  
Deferred Tax Assets, Tax Credit Carryforwards 95 $ 64  
Unrecognized Tax Benefits 62 $ 61 $ 61
Unrecognized Tax Benefits that Would Impact Effective Tax Rate $ 53    
Before Enactment of New Act [Member]      
Operating Loss Carryforwards [Line Items]      
Income Tax, Interest Deductibility Limit 30.00%    
After Enactment of New Act [Member]      
Operating Loss Carryforwards [Line Items]      
Income Tax, Interest Deductibility Limit 50.00%    
Federal Tax [Member]      
Operating Loss Carryforwards [Line Items]      
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration $ 15,000    
Deferred Tax Assets, Tax Credit Carryforwards 93    
Federal Tax [Member] | Investment Tax Credit Carryforward [Member]      
Operating Loss Carryforwards [Line Items]      
Deferred Tax Assets, Tax Credit Carryforwards 52    
State Tax [Member]      
Operating Loss Carryforwards [Line Items]      
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration 3,200    
Deferred Tax Assets, Tax Credit Carryforwards 2    
Foreign Tax Authority      
Operating Loss Carryforwards [Line Items]      
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration 10,600    
Deferred Tax Assets, Tax Credit Carryforwards $ 37