Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions		Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance at Dec. 31, 2013		$ 11,643		$ 13,982	$ 3,049	$ (5,130)	$ (258)
Beginning balance, shares at Dec. 31, 2013			869				18
Consolidated Statements of Stockholders' Equity (Deficit)
Net income		659			659
Dividends declared		(252)			(252)
Other comprehensive income (loss)		(2,181)				(2,181)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes), value	[1]	26		81			$ (55)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes), shares	[1]		3				2
Stock options exercised, value		18		18
Stock options exercised, shares			2
Stock purchased and retired, value		(1,100)		(460)	(640)
Stock purchased and retired, shares			(29)
Ending balance at Dec. 31, 2014		8,813		13,621	2,816	(7,311)	$ (313)
Ending balance, shares at Dec. 31, 2014			845				20
Consolidated Statements of Stockholders' Equity (Deficit)
Net income		4,526			4,526
Dividends declared		(359)			(359)
Other comprehensive income (loss)		36				36
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes), value	[1]	16		76			$ (60)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes), shares	[1]		1				1
Stock options exercised, value		18		18
Stock options exercised, shares			2
Stock purchased and retired, value		(2,200)		(779)	(1,421)
Stock purchased and retired, shares			(48)
Ending balance at Dec. 31, 2015		10,850		12,936	5,562	(7,275)	$ (373)
Ending balance, shares at Dec. 31, 2015			800				21
Consolidated Statements of Stockholders' Equity (Deficit)
Net income		4,373			4,373
Change in accounting principle		95			95
Dividends declared		(509)			(509)
Other comprehensive income (loss)		(361)				(361)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes), value	[1]	65		105			$ (40)
Shares of common stock issued and compensation expense associated with equity awards (Treasury shares withheld for payment of taxes), shares	[1]		2				1
Stock options exercised, value		32		32
Treasury Stock Contributed to Qualified Defined Benefit Pension Plan, Amount		343		204			$ 139
Treasury Stock Contributed to Qualified Defined Benefit Pension Plan, Shares							(8)
Stock options exercised, shares			3
Stock purchased and retired, value		(2,601)		(983)	(1,618)		$ 0
Stock purchased and retired, shares			(60)
Ending balance at Dec. 31, 2016		$ 12,287		$ 12,294	$ 7,903	$ (7,636)	$ (274)
Ending balance, shares at Dec. 31, 2016			745				14

[1] Weighted average price per share