Condensed Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common stock	Paid-in capital	Retained earnings	Accumulated other comprehensive loss
Beginning of year at Dec. 31, 2015		$ 181	$ 0	$ 10,661	$ (5,320)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased		(2)		(284)
Net earnings	$ 556			556
Dividends declared				(147)
Stock compensation		2		(122)
Other comprehensive income, net of tax	96				96
End of period at Mar. 31, 2016	$ 5,621	181	0	10,664	(5,224)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared per share	$ 0.80
Beginning of year at Dec. 31, 2016	$ 5,259	175	0	10,630	(5,546)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock repurchased		(1)		(215)
Net earnings	640			640
Dividends declared				(159)
Stock compensation		1		(72)
Other comprehensive income, net of tax	105				105
End of period at Mar. 31, 2017	$ 5,558	$ 175	$ 0	$ 10,824	$ (5,441)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cash dividends declared per share	$ 0.90