Consolidated Statement of Changes in Equity (Unaudited) - USD ($) $ in Millions	Total	Total	Common Shares	Common Stock and Capital Surplus	Retained Earnings Approp.	Retained Earnings Unapprop.	Accumulated Other Comprehensive Inc. (Loss)	Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change for variable interest entities	$ 2	$ 2			$ 2
Beginning Balance, shares at Dec. 31, 2014			87,708,793
Beginning Balance at Dec. 31, 2014	5,054	4,879		$ 1,240	(2)	$ 2,914	$ 727	$ 175
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	25	19				19		6
Other comprehensive income (loss)	50	49					49	1
Dividends on Common Stock	(22)	(22)				(22)
Shares issued:
Restricted stock awards, shares			171,130
Restricted stock awards	0	0		0
Exercise of stock options, shares			489,001
Exercise of stock options	17	17		17
Other benefit plans, shares			62,094
Other benefit plans	4	4		4
Dividend reinvestment plan, shares			3,606
Stock-based compensation:
Stock-based compensation: Expense	5	5		5
Stock-based compensation: Excess tax benefits	3	3		3
Shares acquired and retired, shares			(516,276)
Shares acquired and retired	(31)	(31)		(8)		(23)
Shares exchanged - benefit plans, shares			(32,633)
Shares exchanged - benefit plans	(2)	(2)				(2)
Other	(5)							(5)
Ending Balance, shares at Mar. 31, 2015			87,885,715
Ending Balance at Mar. 31, 2015	$ 5,100	4,923		1,261	0	2,886	776	177
Beginning Balance, shares at Dec. 31, 2015	87,474,452		87,474,452
Beginning Balance at Dec. 31, 2015	$ 4,770	4,592		1,301	0	2,987	304	178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	104	101				101		3
Other comprehensive income (loss)	146	144					144	2
Dividends on Common Stock	(24)	(24)				(24)
Shares issued:
Restricted stock awards, shares			317,230
Restricted stock awards	0	0		0
Exercise of stock options, shares			279,165
Exercise of stock options	10	10		10
Other benefit plans, shares			47,566
Other benefit plans	3	3		3
Dividend reinvestment plan, shares			3,736
Dividend reinvestment plan	0	0		0
Stock-based compensation:
Stock-based compensation: Expense	5	5		5
Stock-based compensation: Excess tax benefits	2	2		2
Shares acquired and retired, shares			(1,128,128)
Shares acquired and retired	(76)	(76)		(16)		(60)
Shares exchanged - benefit plans, shares			(27,551)
Shares exchanged - benefit plans	(2)	(2)				(2)
Forfeitures of restricted stock, shares			(180)
Forfeitures of restricted stock	0	0		0
Other	$ (1)							(1)
Ending Balance, shares at Mar. 31, 2016	86,966,290		86,966,290
Ending Balance at Mar. 31, 2016	$ 4,937	$ 4,755		$ 1,305	$ 0	$ 3,002	$ 448	$ 182