Annual report pursuant to Section 13 and 15(d)

Income Taxes - Narrative (Details)

v3.10.0.1
Income Taxes - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Operating Loss Carryforwards [Line Items]      
Deferred Tax Assets, Tax Credit Carryforwards $ 28 $ 22  
Deferred Tax Assets, Disallowed Business Interest Expense Carryforward, Percentage of Adjusted Taxable Income Allowed 30.00%    
Disallowed Business Interest Expense Carryforward, Pre-Tax Amount $ 92    
Deferred Foreign Income Tax Benefit 5 $ 3 $ (2)
Valuation Allowance, Deferred Tax Asset, Decrease $ 120    
U.S. corporate income tax rate 21.00% 35.00% 35.00%
Federal Tax [Member]      
Operating Loss Carryforwards [Line Items]      
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration $ 4,300    
Deferred Tax Assets, Tax Credit Carryforwards 25    
Federal Tax [Member] | Investment Tax Credit Carryforward [Member]      
Operating Loss Carryforwards [Line Items]      
Deferred Tax Assets, Tax Credit Carryforwards 14    
State Tax [Member]      
Operating Loss Carryforwards [Line Items]      
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration 2,400    
Deferred Tax Assets, Tax Credit Carryforwards 3    
U.K. Tax [Member]      
Operating Loss Carryforwards [Line Items]      
Deferred Foreign Income Tax Benefit $ 5