Statement of Changes in Total Equity - USD ($) $ in Millions	Total	Shareholders' Equity [Member]	Common Stock [Member]	Additional Paid In Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Other noncontrolling interests [Member]
Total Equity, beginning of period at Dec. 31, 2015	$ 12,044	$ 12,035	$ 74	$ 2,859	$ (1,250)	$ 12,121	$ (1,769)	$ 9
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	17	17		31		(94)	80
Other comprehensive income (loss)	406	406			406
Net income (loss)	1,020	1,029				1,029		(9)
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(110)	(110)					(110)
Other transactions impacting noncontrolling interest	(3)	(11)		(11)				8
Total Equity, end of period at Jun. 30, 2016	13,364	13,356	74	2,879	(844)	13,046	(1,799)	8
Beginning Balance at Dec. 31, 2015	69
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	2
Net income (loss)	(3)
Other transactions impacting noncontrolling interest	3
Ending Balance at Jun. 30, 2016	71
Total Equity, beginning of period at Mar. 31, 2016	12,684	12,675	74	2,874	(988)	12,541	(1,826)	9
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	32	32		10		(5)	27
Other comprehensive income (loss)	144	144			144
Net income (loss)	505	510				510		(5)
Other transactions impacting noncontrolling interest	(1)	(5)		(5)				4
Total Equity, end of period at Jun. 30, 2016	13,364	13,356	74	2,879	(844)	13,046	(1,799)	8
Beginning Balance at Mar. 31, 2016	73
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	(1)
Net income (loss)	(2)
Other transactions impacting noncontrolling interest	1
Ending Balance at Jun. 30, 2016	71
Total Equity, beginning of period at Dec. 31, 2016	13,727	13,723	74	2,892	(1,382)	13,855	(1,716)	4
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	131	131		33		(154)	252
Other comprehensive income (loss)	236	236			236
Net income (loss)	1,406	1,411				1,411		(5)
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(942)	(942)					(942)
Other transactions impacting noncontrolling interest	(1)	(3)		(3)				2
Total Equity, end of period at Jun. 30, 2017	14,547	14,546	74	2,922	(1,146)	15,102	(2,406)	1
Beginning Balance at Dec. 31, 2016	58
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	0
Net income (loss)	(3)
Other transactions impacting noncontrolling interest	3
Ending Balance at Jun. 30, 2017	58
Total Equity, beginning of period at Mar. 31, 2017	14,229	14,226	74	2,912	(1,252)	14,356	(1,864)	3
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	93	93		10		(67)	150
Other comprehensive income (loss)	106	106			106
Net income (loss)	811	813				813		(2)
Repurchase of common stock	(692)	(692)					(692)
Other transactions impacting noncontrolling interest	0	0		0
Total Equity, end of period at Jun. 30, 2017	14,547	$ 14,546	$ 74	$ 2,922	$ (1,146)	$ 15,102	$ (2,406)	$ 1
Beginning Balance at Mar. 31, 2017	56
Redeemable Noncontrolling Interests
Other comprehensive income (loss)	2
Net income (loss)	(1)
Other transactions impacting noncontrolling interest	1
Ending Balance at Jun. 30, 2017	$ 58