Schedule II: Valuation and Qualifying Accounts Schedule II: Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 583	$ 455	$ 763
Additions/Charged to Expense	7,514	7,572	7,682
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	7,339	7,444	7,990
Balance at End of Period	758	583	455
Allowance For Contract With Customer [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	159	162	195
Additions/Charged to Expense	121	85	23
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	143	88	56
Balance at End of Period	137	159	162
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	331	162	126
Additions/Charged to Expense	3	170	72
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	117	1	36
Balance at End of Period	$ 217	$ 331	$ 162