Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Shares	Paid-in Capital in Excess of Par Value	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling interest in Consolidated Subsidiaries
Beginning balance at Dec. 31, 2013	$ (13,615)	$ (2,680)	$ (415)	$ (8,049)	$ (18,842)	$ 307	$ (34)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	3,501	0	0	0	3,500	0	1
Other comprehensive income (loss)	(92)	0	0	0	0	(92)	0
Common shares repurchased	(800)	0	0	(800)	0	0	0
Cash dividends	(533)	0	0	0	(533)	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							0
Stock plans	556	1	161	718	0	0	0
Other	51	0	55	0	0	0	(4)
Ending balance at Dec. 31, 2014	(16,298)	(2,679)	(309)	(8,131)	(21,809)	399	(31)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(667)	0	0	0	(671)	0	4
Other comprehensive income (loss)	36	0	0	0	0	36	0
Cash dividends	(614)	0	0	0	(614)	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							0
Stock plans	440	2	39	481	0	0	0
Other	2	0	4	0	0	0	(2)
Ending balance at Dec. 31, 2015	(15,495)	(2,677)	(274)	(7,650)	(20,524)	363	(33)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(5,769)	0	0	0	(5,763)	0	(6)
Other comprehensive income (loss)	(91)	0	0	0	0	(91)	0
Cash dividends	(620)	0	0	0	(620)	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders							0
Stock plans	425	3	69	497	0	0	0
Other	(8)	0	(4)	0	0	0	12
Ending balance at Dec. 31, 2016	$ (9,448)	$ (2,674)	$ (201)	$ (7,153)	$ (14,141)	$ 454	$ (39)