Revenue Recognition Contract Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Contract with Customer, Asset, Allowance for Credit Loss [Roll Forward]
Contract with Customer, Liability	$ 1,331	$ 1,535	$ 1,397	$ 1,596
Contract with Customer, Liability, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress	12	58	138	269
Contract With Customer Liability Increase Decrease For Contract Deconsolidated	0	0	0	(52)
ContractLiabilityNoncashInterestExpenseSignificantFinancingObligation	3	4	10	11
Contract with Customer, Liability, Revenue Recognized	(77)	(112)	(276)	(339)
Contract with Customer, Liability	$ 1,269	$ 1,485	$ 1,269	$ 1,485