Annual report pursuant to Section 13 and 15(d)

Accounts Receivable Accounts Receivable (Activity in the Allowance for Doubtful Accounts) (Details)

v3.19.3.a.u2
Accounts Receivable Accounts Receivable (Activity in the Allowance for Doubtful Accounts) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Accounts Receivable, Allowance for Credit Loss [Roll Forward]      
Balance beginning of year $ 112 $ 91 $ 97
Additions- charged to expense 124 112 72
Deductions- write-offs (113) (91) (78)
Balance end of year $ 123 $ 112 $ 91