Basis Of Presentation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019
Basis of Presentation [Line Items]
Operating Lease, Liability	$ 1,117		$ 1,117
Increase/(Decrease) in revenue due to change in accounting estimate	69	$ (72)	229	$ 45
Increase/(Decrease) in Earnings from operations due to change in accounting estimate	$ 28	$ (237)	$ 175	$ (159)
Change in Earnings Per Share Due to Change in Accounting Estimate	$ 0.04	$ (0.34)	$ 0.22	$ (0.23)
Accounting Standards Update 2016-02 [Member]
Basis of Presentation [Line Items]
Operating Lease, Liability	$ 1,117		$ 1,117		$ 1,064