2018 Impact of Accounting Method Change (Details 1) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
General and Administrative Expense									$ 3,011	$ 2,712	$ 2,632
Operating Income (Loss)	$ 943	$ 1,172	$ 817	$ 848	$ 672	$ 829	$ 864	$ 853	3,780	3,218	3,277
Interest and Debt Expense									(562)	(360)	(301)
Net FAS (non-service) pension benefit									1,049	699	611
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit									(655)	536	(950)
Other Nonoperating Income (Expense)									130	136	44
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									3,742	4,229	2,681
Income Tax Expense (Benefit)									513	1,360	638
Net Income (Loss) Attributable to Parent	$ 356	$ 1,244	$ 789	$ 840	$ 672	$ 750	$ 677	$ 770	$ 3,229	$ 2,869	$ 2,043
Earnings Per Share, Basic	$ 2.07	$ 7.15	$ 4.52	$ 4.82	$ 3.86	$ 4.31	$ 3.88	$ 4.41	$ 18.59	$ 16.45	$ 11.42
Earnings Per Share, Diluted	$ 2.06	$ 7.11	$ 4.50	$ 4.79	$ 3.83	$ 4.28	$ 3.86	$ 4.37	$ 18.49	$ 16.34	$ 11.32
Adjustments for change to Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Period Benefit (Cost) [Member] | Adjustments for Change in Accounting Principle [Domain]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
General and Administrative Expense										$ 0	$ 0
Operating Income (Loss)	$ 23	$ (6)	$ (6)	$ (6)	$ (32)	$ (8)	$ (9)	$ (9)	$ 5	(58)	8
Interest and Debt Expense									0	0	0
Net FAS (non-service) pension benefit									535	743	752
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit									(655)	536	(950)
Other Nonoperating Income (Expense)									(2)	12	16
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									(117)	1,233	(174)
Income Tax Expense (Benefit)									(24)	359	(61)
Net Income (Loss) Attributable to Parent	$ (394)	$ 100	$ 100	$ 101	$ 525	$ 107	$ 122	$ 120	$ (93)	$ 874	$ (113)
Earnings Per Share, Basic	$ (2.29)	$ 0.58	$ 0.57	$ 0.58	$ 3.01	$ 0.62	$ 0.70	$ 0.69	$ (0.53)	$ 5.01	$ (0.63)
Earnings Per Share, Diluted	$ (2.28)	$ 0.57	$ 0.57	$ 0.58	$ 2.99	$ 0.61	$ 0.70	$ 0.68	$ (0.54)	$ 4.98	$ (0.63)
Method Prior to change to Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Period Benefit (Cost) [Member] [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Income (Loss)									$ 3,775
Interest and Debt Expense									(562)
Net FAS (non-service) pension benefit									514
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit									0
Other Nonoperating Income (Expense)									132
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									3,859
Income Tax Expense (Benefit)									537
Net Income (Loss) Attributable to Parent									$ 3,322
Earnings Per Share, Basic									$ 19.12
Earnings Per Share, Diluted									$ 19.03
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Income (Loss) Attributable to Parent										$ 2,869	$ 2,043
Retained Earnings [Member] | Adjustments for change to Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Period Benefit (Cost) [Member] | Adjustments for Change in Accounting Principle [Domain]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Income (Loss) Attributable to Parent										$ 874	$ (113)