Reorganization of Businesses (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) employee	Dec. 31, 2015 USD ($) employee	Dec. 31, 2014 USD ($) employee	Dec. 31, 2013 USD ($)
Restructuring Cost and Reserve [Line Items]
Maximum severance benefits salary period	6 months
Reorganization of business charges	$ 140	$ 117	$ 73
Restructuring reserve	101	60	57	$ 109
Additional charges	125	84	100
Cash payments for exit costs	79	71	148
Net adjustment of accruals	(5)	(10)	(4)
Exit costs
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	7	9	0	6
Additional charges	5	10	7
Cash payments for exit costs	6	1	13
Net adjustment of accruals	(1)	0	0
Employee separation costs
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	94	51	57	$ 103
Additional charges	120	74	93
Cash payments for exit costs	$ 73	$ 70	$ 135
Restructuring charges in the period for total employee severance (in number of employees) | employee	1,300	1,100	1,200
Restructuring charges in the period for direct employees' severance (in number of employees) | employee	400	200	300
Restructuring charges in the period for indirect employees' severance (in number of employees) | employee	900	900	900
Net adjustment of accruals	$ (4)	$ (10)	$ (4)
Number of employees expected to be paid (in number of employees) | employee	300
Continuing Operations
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	$ 140	117	73
Net adjustment of accruals	(5)	(4)	(1)
Continuing Operations | Exit costs
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	5	10	7
Continuing Operations | Employee separation costs
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	120	74	67
Discontinued Operations | Employee separation costs
Restructuring Cost and Reserve [Line Items]
Additional charges			26
Cash payments for exit costs			50
Net adjustment of accruals		(6)
Air Transportation Equipment | Asset Impairment Due Reorganization
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	3	31
Building | Asset Impairment Due Reorganization
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	17	6
Costs of sales | Continuing Operations
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	43	9	9
Other charges | Continuing Operations
Restructuring Cost and Reserve [Line Items]
Reorganization of business charges	$ 97	$ 108	$ 64