Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 86	$ 101	$ 105
Balance Acquired through Acquisitions	0	0	0
Charged to Costs and Expenses	26	26	31
Deductions	26	41	35
Balance at End of Period	86	86	101
Valuation allowance on deferred tax assets [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	841	1,120	1,108
Balance Acquired through Acquisitions	0	0	218
Charged to Costs and Expenses	76	37	157
Deductions	366	316	363
Balance at End of Period	551	841	1,120
Reserve for inventory obsolescence [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	56	67	59
Balance Acquired through Acquisitions	0	0	0
Charged to Costs and Expenses	11	5	26
Deductions	6	16	18
Balance at End of Period	$ 61	$ 56	$ 67