Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated other comprehensive income (loss):
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of changes in accounting principle	$ 2			$ 2
AOCI, beginning balance at Dec. 31, 2018	11,424	$ 6	$ 47	11,485	$ (114)
Beginning balance, shares at Dec. 31, 2018		577
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	441			441
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent					40
Other comprehensive income (loss)	40
Common stock issued, stock-based compensation plans - value	50		50
Common stock issued, stock-based compensation plans - shares		2
Stock-based compensation expense	66		66
Repurchases of common stock, Value	(771)		(99)	(672)
Repurchases of common stock, Shares		(10)
Dividends declared, $0.22 per share	(116)			(116)
AOCI, ending balance at Mar. 31, 2019	11,136	$ 6	64	11,140	(74)
Ending balance, shares at Mar. 31, 2019		569
AOCI, beginning balance at Dec. 31, 2018	11,424	$ 6	47	11,485	(114)
Beginning balance, shares at Dec. 31, 2018		577
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	950
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	44				44
AOCI, ending balance at Jun. 30, 2019	10,557	$ 6	38	10,583	(70)
Ending balance, shares at Jun. 30, 2019		552
AOCI, beginning balance at Mar. 31, 2019	11,136	$ 6	64	11,140	(74)
Beginning balance, shares at Mar. 31, 2019		569
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	509			509
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	4				4
Other comprehensive income (loss)	4
Common stock issued, stock-based compensation plans - value	40		40
Common stock issued, stock-based compensation plans - shares		2
Stock-based compensation expense	54		54
Repurchases of common stock, Value	(1,072)		(120)	(952)
Repurchases of common stock, Shares		(19)
Dividends declared, $0.22 per share	(114)			(114)
AOCI, ending balance at Jun. 30, 2019	10,557	$ 6	38	10,583	(70)
Ending balance, shares at Jun. 30, 2019		552
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of changes in accounting principle	1			1
AOCI, beginning balance at Dec. 31, 2019	$ 11,022	$ 5	33	11,022	(38)
Beginning balance, shares at Dec. 31, 2019	548	548
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 367			367
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent					(226)
Other comprehensive income (loss)	(226)
Common stock issued, stock-based compensation plans - value	40		40
Common stock issued, stock-based compensation plans - shares		2
Stock-based compensation expense	55		55
Repurchases of common stock, Value	(526)		(87)	(439)
Repurchases of common stock, Shares		(9)
Dividends declared, $0.22 per share	(120)			(120)
AOCI, ending balance at Mar. 31, 2020	10,613	$ 5	41	10,831	(264)
Ending balance, shares at Mar. 31, 2020		541
AOCI, beginning balance at Dec. 31, 2019	$ 11,022	$ 5	33	11,022	(38)
Beginning balance, shares at Dec. 31, 2019	548	548
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 728
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(150)				(150)
AOCI, ending balance at Jun. 30, 2020	$ 10,972	$ 5	83	11,072	(188)
Ending balance, shares at Jun. 30, 2020	542	542
AOCI, beginning balance at Mar. 31, 2020	$ 10,613	$ 5	41	10,831	(264)
Beginning balance, shares at Mar. 31, 2020		541
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	361
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	76				76
Other comprehensive income (loss)	76
Common stock issued, stock-based compensation plans - value	36		36
Common stock issued, stock-based compensation plans - shares		2
Stock-based compensation expense	65		65
Repurchases of common stock, Value	(59)		(59)	0
Repurchases of common stock, Shares		(1)
Dividends declared, $0.22 per share	(120)			(120)
AOCI, ending balance at Jun. 30, 2020	$ 10,972	$ 5	$ 83	$ 11,072	$ (188)
Ending balance, shares at Jun. 30, 2020	542	542