Employee Benefit Obligations - Other Post-Retirement Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in projected benefit obligation:
Service cost		$ 72,000,000	$ 67,000,000	$ 60,000,000
Interest cost		154,000,000	75,000,000	88,000,000
Components of net periodic benefit cost:
Service cost		72,000,000	67,000,000	60,000,000
Interest cost		154,000,000	75,000,000	88,000,000
Amortization of prior service cost		(1,000,000)	(1,000,000)	(1,000,000)
Recognized net actuarial loss		38,000,000	48,000,000	38,000,000
Total net periodic benefit cost		$ 169,000,000	96,000,000	132,000,000
Deferred Compensation Plans
Employer match of deferred compensation (as a percent)		20.00%
Employer contribution limit per calendar year		$ 20,000
Number of shares, value equivalent, for each stock unit		1
Other Benefit Plans
Percentage of eligible compensation, matched 100% by employer		3.00%
Percentage of eligible compensation, matched 50% by employer		2.00%
Employer match of employee contributions of first 3% of eligible compensation (as a percent)		100.00%
Employer match of employee contributions of next 2% of eligible compensation (as a percent)		50.00%
Expense associated with the company match		$ 25,000,000	24,000,000	24,000,000
Aerospace
Other Benefit Plans
Performance-based matching cash contributions by employer limit (as a percent of base salary)		4.00%
Additional compensation expense related to performance-based program recognized		$ 0	0	5,000,000
Other post retirement benefits
Change in projected benefit obligation:
Benefit obligation at prior year end	$ 232,000,000	135,000,000	154,000,000
Service cost		3,000,000	2,000,000	2,000,000
Interest cost		8,000,000	6,000,000	7,000,000
Benefits paid		(16,000,000)	(9,000,000)
Net actuarial (gains) losses		(18,000,000)	(17,000,000)
Net transfer in due to acquisition		120,000,000
Special termination benefits			2,000,000
Effect of exchange rates			(3,000,000)
Benefit obligation at year end		232,000,000	135,000,000	154,000,000
Components of net periodic benefit cost:
Service cost		3,000,000	2,000,000	2,000,000
Interest cost		8,000,000	6,000,000	7,000,000
Amortization of prior service cost		(1,000,000)	(1,000,000)	(1,000,000)
Recognized net actuarial loss		(3,000,000)	(2,000,000)	(1,000,000)
Defined Benefit Plan, Actuarial Gain (Loss)		18,000,000	17,000,000
Total net periodic benefit cost		7,000,000	$ 7,000,000	$ 7,000,000
Increase in the postretirement benefit obligation due to one-percentage point increase in assumed health care cost trend rate		8,000,000
Decrease in the postretirement benefit obligation due to one-percentage point decrease in assumed health care cost trend rate		(6,000,000)
Expected benefit payments
Years 2022 through 2026		94,000,000
Other post retirement benefits | Minimum
Expected benefit payments
2017		22,000,000
2018		22,000,000
2019		22,000,000
2020		22,000,000
2021		22,000,000
Other post retirement benefits | Maximum
Components of net periodic benefit cost:
Increase in the total of service and interest cost due to one-percentage point increase in assumed health care cost trend rate		1,000,000
Decrease in the total of service and interest cost due to one-percentage point decrease in assumed health care cost trend rate		(1,000,000)
Expected benefit payments
2017		24,000,000
2018		24,000,000
2019		24,000,000
2020		24,000,000
2021		$ 24,000,000
Other post retirement benefits | Forecast
Expected benefit payments
Pension Contributions	$ 24,000,000
U.S. health care plans
Components of net periodic benefit cost:
Health care cost trend rate used for pre-65 and post-65 benefits (as a percent)		7.00%
Rate to which the health care cost trend rate is assumed to decline (as a percent)			5.00%
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)		4.16%	4.60%	4.15%
Rate of compensation increase (as a percent)		4.50%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)		4.04%	4.15%	5.00%
Rate of compensation increase (as a percent)		4.50%
Canadian plans
Components of net periodic benefit cost:
Health care cost trend rate used for pre-65 and post-65 benefits (as a percent)		4.75%
Rate to which the health care cost trend rate is assumed to decline (as a percent)		5.00%
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)		3.50%	3.50%	3.50%
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)		3.50%	3.50%	4.25%