Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common stock	Paid-in capital	Retained earnings	Accumulated other comprehensive (loss) income
Beginning of period at Dec. 31, 2018		$ 171	$ 0	$ 8,068	$ (52)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased		(2)	0	(234)
Net earnings	$ 1,724			1,724
Dividends declared				(432)
Stock compensation			0	(6)
Other				0
Other comprehensive loss, net of tax	(23)				(23)
End of period at Jun. 30, 2019	$ 9,214	169	0	9,120	(75)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared per share	$ 2.52
Beginning of period at Mar. 31, 2019		170	0	8,628	(59)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased		(1)	0	(172)
Net earnings	$ 861			861
Dividends declared				(226)
Stock compensation			0	29
Other				0
Other comprehensive loss, net of tax	(16)				(16)
End of period at Jun. 30, 2019	$ 9,214	169	0	9,120	(75)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared per share	$ 1.32
Beginning of period at Dec. 31, 2019	$ 8,819	168	0	8,748	(97)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased		(1)	0	(479)
Net earnings	1,873			1,873
Dividends declared				(465)
Stock compensation			10	(36)
Other				11
Other comprehensive loss, net of tax	(20)				(20)
End of period at Jun. 30, 2020	$ 9,712	167	10	9,652	(117)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared per share	$ 2.77
Beginning of period at Mar. 31, 2020		167	0	9,011	(116)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased		0	0	(131)
Net earnings	$ 1,005			1,005
Dividends declared				(242)
Stock compensation			10	9
Other				0
Other comprehensive loss, net of tax	(1)				(1)
End of period at Jun. 30, 2020	$ 9,712	$ 167	$ 10	$ 9,652	$ (117)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared per share	$ 1.45