Other Comprehensive Income (Loss) - Changes in AOCI balance by Component (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Pension and Other Post-Employment Benefits
Other Comprehensive Income (Loss)
Beginning balance	$ (580)
Income Before Reclassifications	86
Amounts Reclassified to Net Earnings	33
Tax Expense	(43)
Total Other Comprehensive Income	76
Ending balance	(504)
Other
Other Comprehensive Income (Loss)
Beginning balance	(60)
Income Before Reclassifications	2
Amounts Reclassified to Net Earnings	2
Tax Expense	(1)
Total Other Comprehensive Income	3
Ending balance	(57)
Accumulated Other Comprehensive Income (Loss)
Other Comprehensive Income (Loss)
Beginning balance	(640)
Income Before Reclassifications	88
Amounts Reclassified to Net Earnings	35
Tax Expense	(44)
Total Other Comprehensive Income	79
Ending balance	$ (561)