Other Comprehensive Income (Loss) - Changes in AOCI balance by Component (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019
Other Comprehensive Income (Loss)
Loss Before Reclassifications						$ (5)
Amounts Reclassified to Net Earnings						15
Tax Expense						(4)
Total Other Comprehensive Income (Loss)		$ 4	$ 2	$ 4	$ (99)	6
Pension and Other Post-Employment Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance December 31, 2018, Net of Tax			(604)			(604)
Other Comprehensive Income (Loss)
Loss Before Reclassifications						0
Amounts Reclassified to Net Earnings						12
Tax Expense						(3)
Total Other Comprehensive Income (Loss)						9
Balance June 30, 2019, Net of Tax		(595)				(595)
Other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance December 31, 2018, Net of Tax			(57)			(57)
Other Comprehensive Income (Loss)
Loss Before Reclassifications						(5)
Amounts Reclassified to Net Earnings						3
Tax Expense						(1)
Total Other Comprehensive Income (Loss)						(3)
Balance June 30, 2019, Net of Tax		(60)				(60)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance December 31, 2018, Net of Tax			(661)			(661)
Other Comprehensive Income (Loss)
Total Other Comprehensive Income (Loss)	[1]	4	$ 2	$ 4	$ (99)
Balance June 30, 2019, Net of Tax		$ (655)				$ (655)

[1] Accumulated Other Comprehensive Loss balances shown above are net of tax. The associated taxes were $179 million and $177 million as of first and second quarters 2019, and $160 million and $158 million as of first and second quarters 2018, respectively. For additional information, see Note 12, Other Comprehensive Income.