Equity (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		6 Months Ended
		Jul. 20, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reconciliation of the Beginning and Ending Balances of the Carrying Amounts of Equity
Balance as of beginning of period					$ 20,854	$ 21,354
Net income			$ 572	$ 843	893	1,356
Dividends					(627)	(564)
Stock-based compensation expense					25	23
Distributions to noncontrolling interests					(45)	(47)
Other					40	3
Other comprehensive income (loss)			211	(200)	287	(68)
Balance as of end of period			20,765	21,404	20,765	21,404
Dividend Declared [Member] | Subsequent Event [Member]
Equity (Textual)
Dividends payable, date declared		Jul. 20, 2017
Dividends payable, amount per share		$ 0.70
Dividends payable, date to be paid		Sep. 07, 2017
Dividends payable, date of record		Aug. 09, 2017
Stock-Based Compensation Plans Purchase Program [Member]
Reconciliation of the Beginning and Ending Balances of the Carrying Amounts of Equity
Stock purchases					(13)	(43)
Common Stock Purchase Program [Member]
Reconciliation of the Beginning and Ending Balances of the Carrying Amounts of Equity
Stock purchases					(649)	(610)
Parent [Member]
Reconciliation of the Beginning and Ending Balances of the Carrying Amounts of Equity
Balance as of beginning of period					20,024	20,527
Net income					853	1,309
Dividends					(627)	(564)
Stock-based compensation expense					25	23
Distributions to noncontrolling interests					0	0
Other					23	3
Other comprehensive income (loss)					287	(69)
Balance as of end of period			19,923	20,576	19,923	20,576
Parent [Member] | Stock-Based Compensation Plans Purchase Program [Member]
Reconciliation of the Beginning and Ending Balances of the Carrying Amounts of Equity
Stock purchases					(13)	(43)
Parent [Member] | Common Stock Purchase Program [Member]
Reconciliation of the Beginning and Ending Balances of the Carrying Amounts of Equity
Stock purchases					(649)	(610)
Noncontrolling Interests [Member]
Reconciliation of the Beginning and Ending Balances of the Carrying Amounts of Equity
Balance as of beginning of period	[1]				830	827
Net income	[1]				40	47
Distributions to noncontrolling interests	[1]				(45)	(47)
Other	[1]				17	0
Other comprehensive income (loss)	[1]				0	1
Balance as of end of period	[1]		$ 842	$ 828	$ 842	$ 828

[1] The noncontrolling interests relate to third-party ownership interests in VIEs for which we are the primary beneficiary and therefore consolidate. See Note 7 for information about our consolidated VIEs.