Stockholders' Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent, Net of Tax
Accumulated other comprehensive income (loss) beginning balance			$ (662)	$ (767)
Other comprehensive income (loss) before reclassifications			(14)	2
Reclassifications to net earnings (loss)			30	24
Total other comprehensive income, net of tax	$ 7	$ 12	16	26
Accumulated other comprehensive income (loss) ending balance	(646)	(741)	(646)	(741)
Cumulative Translation Adjustments [Member]
AOCI Attributable to Parent, Net of Tax
Accumulated other comprehensive income (loss) beginning balance			159	151
Other comprehensive income (loss) before reclassifications			(14)	2
Reclassifications to net earnings (loss)			0	0
Total other comprehensive income, net of tax			(14)	2
Accumulated other comprehensive income (loss) ending balance	145	153	145	153
Net Actuarial Loss and Prior Service Cost [Member]
AOCI Attributable to Parent, Net of Tax
Accumulated other comprehensive income (loss) beginning balance			(821)	(918)
Other comprehensive income (loss) before reclassifications			0	0
Reclassifications to net earnings (loss)			30	24
Total other comprehensive income, net of tax			30	24
Accumulated other comprehensive income (loss) ending balance	$ (791)	$ (894)	$ (791)	$ (894)