Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Allowance for Doubtful Accounts) (Details)

v3.10.0.1
Summary of Significant Accounting Policies (Allowance for Doubtful Accounts) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Accounting Changes and Error Corrections [Abstract]      
Schedule of Accounts Receivable
The following table illustrates the Company’s allowance for doubtful accounts activity for the year ended December 31:
 
2018
 
2017
 
2016
Beginning Balance
$
61

 
$
77

 
$
98

Bad debt expense
8

 
7

 
3

Write-offs
(17
)
 
(23
)
 
(24
)
Ending Balance
$
52

 
$
61

 
$
77

   
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Beginning Balance $ 61 $ 77 $ 98
Bad debt expense 8 7 3
Write-offs (17) (23) (24)
Ending Balance $ 52 $ 61 $ 77