Condensed Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Capital In Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balances at Dec. 31, 2016	$ 10,685	$ 33	$ 2,562	$ 11,454	$ (66)	$ (3,298)
Balances (in shares) at Dec. 31, 2016		198,495
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,264			2,264
Other comprehensive income (loss)	78				78
Common stock repurchases	(1,819)					(1,819)
Dividends and dividend equivalents	(176)			(176)
Stock-based compensation	116		116
Restricted stock unit vesting	0		(100)			100
Stock option exercises	63	$ 0	63
Stock option exercises (in shares)		77
Balances at Sep. 30, 2017	11,211	$ 33	2,641	13,542	12	(5,017)
Balances (in shares) at Sep. 30, 2017		198,572
Balances at Jun. 30, 2017	10,953	$ 33	2,306	13,101	(5)	(4,482)
Balances (in shares) at Jun. 30, 2017		198,570
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	499			499
Other comprehensive income (loss)	17				17
Common stock repurchases	(241)		300			(541)
Dividends and dividend equivalents	(58)			(58)
Stock-based compensation	33		33
Restricted stock unit vesting	0		(6)			6
Stock option exercises	8	$ 0	8
Stock option exercises (in shares)		2
Balances at Sep. 30, 2017	11,211	$ 33	2,641	13,542	12	(5,017)
Balances (in shares) at Sep. 30, 2017		198,572
Balances at Dec. 31, 2017	9,842	$ 33	2,445	13,670	19	(6,325)
Balances (in shares) at Dec. 31, 2017		198,572
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,328			1,328
Other comprehensive income (loss)	(225)
Other comprehensive loss	(229)			(4)	(225)
Common stock repurchases	(294)		200			(494)
Dividends and dividend equivalents	(208)			(208)
Stock-based compensation	105		105
Restricted stock unit vesting	0		(92)			92
Stock option exercises	49	$ 0	49
Stock option exercises (in shares)		21
Balances at Sep. 30, 2018	10,593	$ 33	2,707	14,786	(206)	(6,727)
Balances (in shares) at Sep. 30, 2018		198,593
Balances at Jun. 30, 2018	10,211	$ 33	2,672	14,211	(176)	(6,529)
Balances (in shares) at Jun. 30, 2018		198,591
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	644			644
Other comprehensive income (loss)	(30)				(30)
Common stock repurchases	(201)					(201)
Dividends and dividend equivalents	(69)			(69)
Stock-based compensation	35		35
Restricted stock unit vesting	0		(3)			3
Stock option exercises	3	$ 0	3
Stock option exercises (in shares)		2
Balances at Sep. 30, 2018	$ 10,593	$ 33	$ 2,707	$ 14,786	$ (206)	$ (6,727)
Balances (in shares) at Sep. 30, 2018		198,593