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]	Noncontrolling Interest [Member]
Total Equity, beginning of period at Dec. 31, 2014	$ 10,789	$ 10,774	$ 74	$ 2,769	$ (936)	$ 10,289	$ (1,422)	$ 15
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	115	115		69		(222)	268
Other comprehensive income (loss)	(189)	(189)			(189)
Net income (loss)	1,116	1,121				1,121		(5)
Common dividends declared (per share: $0.04)	(10)	(10)				(10)
Repurchase of common stock	(518)	(518)					(518)
Other transactions impacting noncontrolling interest	0	(3)		(3)				3
Total Equity, end of period at Jun. 30, 2015	11,303	11,290	74	2,835	(1,125)	11,178	(1,672)	13
Beginning Balance at Dec. 31, 2014	90
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(12)
Net income (loss)	(1)
Other transactions impacting noncontrolling interest	(1)
Ending Balance at Jun. 30, 2015	76
Total Equity, beginning of period at Mar. 31, 2015	10,958	10,942	74	2,823	(934)	10,635	(1,656)	16
Increase (Decrease) In Stockholders Equity [Roll Forward]
Effect of issuing stock for employee benefit plans	53	53		14		(45)	84
Other comprehensive income (loss)	(191)	(191)			(191)
Net income (loss)	585	588				588		(3)
Repurchase of common stock	(100)	(100)					(100)
Other transactions impacting noncontrolling interest	(2)	(2)		(2)
Total Equity, end of period at Jun. 30, 2015	11,303	11,290	74	2,835	(1,125)	11,178	(1,672)	13
Beginning Balance at Mar. 31, 2015	83
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income (loss)	(3)
Net income (loss)	(1)
Other transactions impacting noncontrolling interest	(3)
Ending Balance at Jun. 30, 2015	76
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 Interest [Roll Forward]
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 Interest [Roll Forward]
Other comprehensive income (loss)	(1)
Net income (loss)	(2)
Other transactions impacting noncontrolling interest	1
Ending Balance at Jun. 30, 2016	$ 71