Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Treasury Common Stock	AOCI	AOCI Cumulative Effect, Period of Adoption, Adjustment
Balance, beginning balance at Dec. 31, 2017		$ 1,741	$ 1,776	$ 34,662		$ (27,458)	$ (384)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 5,580			5,580
Dividends declared and paid				(2,555)
Common stock issued for stock-based awards			(55)			428
Stock repurchases						(5,100)
Stock compensation			232
Other comprehensive income (loss), net of taxes	(59)						(59)
Dividend equivalents on RSUs				(17)
Other			(3)
Balance, ending balance at Dec. 31, 2018		1,741	1,950	37,906	$ 236	(32,130)	(473)	$ (30)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,017			5,017
Dividends declared and paid				(3,008)
Common stock issued for stock-based awards			(55)			594
Stock repurchases						(2,960)
Stock compensation			217
Other comprehensive income (loss), net of taxes	126						126
Dividend equivalents on RSUs				(17)
Other			(2)			1
Balance, ending balance at Dec. 31, 2019	8,907	1,741	2,110	39,898		(34,495)	(347)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,595			5,595
Dividends declared and paid				(3,426)
Common stock issued for stock-based awards						470
Stock repurchases						(2,553)
Stock compensation			224
Other comprehensive income (loss), net of taxes	(13)						(13)
Dividend equivalents on RSUs				(16)
Other			(1)
Balance, ending balance at Dec. 31, 2020	$ 9,187	$ 1,741	$ 2,333	$ 42,051		$ (36,578)	$ (360)