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	174	160				160		14
Other comprehensive income (loss)	(166)	(164)					(164)	(2)
Dividends on Common Stock	(44)	(44)				(44)
Shares issued:
Restricted stock awards, shares			171,130
Restricted stock awards	0	0		0
Exercise of stock options, shares			852,691
Exercise of stock options	28	28		28
Other benefit plans, shares			88,181
Other benefit plans	5	5		5
Dividend reinvestment plan, shares			7,041
Stock-based compensation:
Stock-based compensation: Expense	10	10		10
Stock-based compensation: Excess tax benefits	6	6		6
Shares acquired and retired, shares			(1,254,791)
Shares acquired and retired	(78)	(78)		(18)		(60)
Shares exchanged - benefit plans, shares			(32,633)
Shares exchanged - benefit plans	(2)	(2)				(2)
Other	(5)							(5)
Ending Balance, shares at Jun. 30, 2015			87,540,412
Ending Balance at Jun. 30, 2015	$ 4,984	4,802		1,271	0	2,968	563	182
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	167	155				155		12
Other comprehensive income (loss)	371	365					365	6
Dividends on Common Stock	(48)	(48)				(48)
Shares issued:
Restricted stock awards, shares			317,230
Restricted stock awards	0	0		0
Exercise of stock options, shares			448,136
Exercise of stock options	16	16		16
Other benefit plans, shares			72,050
Other benefit plans	5	5		5
Dividend reinvestment plan, shares			7,427
Dividend reinvestment plan	1	1		1
Stock-based compensation:
Stock-based compensation: Expense	10	10		10
Stock-based compensation: Excess tax benefits	4	4		4
Shares acquired and retired, shares			(1,438,142)
Shares acquired and retired	(98)	(98)		(22)		(76)
Shares exchanged - benefit plans, shares			(28,044)
Shares exchanged - benefit plans	(2)	(2)				(2)
Forfeitures of restricted stock, shares			(2,650)
Forfeitures of restricted stock	0	0		0
Other	$ (3)							(3)
Ending Balance, shares at Jun. 30, 2016	86,850,459		86,850,459
Ending Balance at Jun. 30, 2016	$ 5,193	$ 5,000		$ 1,315	$ 0	$ 3,016	$ 669	$ 193