Basis Of Presentation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2019
Basis of Presentation [Line Items]
Operating Lease, Liability	$ 1,229		$ 1,229
Increase/(Decrease) in revenue due to change in accounting estimate	(63)	$ (59)	166	$ (14)
Increase/(Decrease) in Earnings from operations due to change in accounting estimate	$ (23)	$ (155)	$ 152	$ (314)
Change in Earnings Per Share Due to Change in Accounting Estimate	$ (0.04)	$ (0.30)	$ 1.20	$ (0.50)
Accounting Standards Update 2016-02 [Member]
Basis of Presentation [Line Items]
Operating Lease, Liability	$ 1,229		$ 1,229		$ 1,064