Basis Of Presentation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basis of Presentation [Line Items]
Operating Lease, Liability	$ 1,064
Increase/(Decrease) in revenue due to change in accounting estimate	160	$ 117
Increase/(Decrease) in Earnings from operations due to change in accounting estimate	$ 147	$ 78
Change in Earnings Per Share Due to Change in Accounting Estimate	$ 0.24	$ 0.11
Accounting Standards Update 2016-02 [Member]
Basis of Presentation [Line Items]
Operating Lease, Liability	$ 1,064