Other Comprehensive Income Information (Amounts Reclassified Out Of Acc Other Comp Income) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Other Comprehensive Income Loss Before Tax [Abstract]
Amortization and settlement of postretirement benefits reserves adjustment included in net periodic benefit costs	[1]	$ (359)	$ (414)

[1] These accumulated other comprehensive income components are included in the computation of net periodic pension cost. (See Note 6 - Pension and Other Postretirement Benefits for additional details.)