Stockholders' Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax
Accumulated other comprehensive income (loss) beginning balance	$ (1,970)	$ (1,608)
Other comprehensive income before reclassifications	8	(62)
Reclassifications to net earnings	52	46
Other comprehensive income (loss)	60	(16)
Tax effects reclassified to retained earnings		(230)
Accumulated other comprehensive income (loss) ending balance	(1,910)	(1,854)
Tax provision on net actuarial gain (loss) and prior service costs related to pension and other postretirement benefit plans	16	15
Cumulative Translation Adjustments [Member]
AOCI Attributable to Parent, Net of Tax
Accumulated other comprehensive income (loss) beginning balance	(463)	(476)
Other comprehensive income before reclassifications	8	(62)
Reclassifications to net earnings	0	0
Other comprehensive income (loss)	8	(62)
Tax effects reclassified to retained earnings		0
Accumulated other comprehensive income (loss) ending balance	(455)	(538)
Net Actuarial Loss and Prior Service Cost [Member]
AOCI Attributable to Parent, Net of Tax
Accumulated other comprehensive income (loss) beginning balance	(1,507)	(1,132)
Other comprehensive income before reclassifications	0	0
Reclassifications to net earnings	52	46
Other comprehensive income (loss)	52	46
Tax effects reclassified to retained earnings		(230)
Accumulated other comprehensive income (loss) ending balance	$ (1,455)	$ (1,316)