Consolidated Statement of Changes in Equity (Unaudited) - USD ($) $ in Millions	Total	Total	Common Shares	Common Stock and Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income	Noncontrolling interests
Beginning Balance, shares at Dec. 31, 2015			87,474,452
Beginning Balance at Dec. 31, 2015	$ 4,770	$ 4,592		$ 1,301	$ 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:
Exercise of stock options, shares			448,136
Exercise of stock options	16	16		16
Restricted stock awards, shares			317,230
Restricted stock awards	0	0		0
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 expense	14	14		14
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)		0	(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
Ending Balance at Jun. 30, 2016	$ 5,193	5,000		1,315	3,016	669	193
Beginning Balance, shares at Dec. 31, 2016	86,924,399		86,924,399
Beginning Balance at Dec. 31, 2016	$ 4,919	4,916		1,198	3,343	375	3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	300	298			298		2
Other comprehensive income (loss)	240	240				240	0
Dividends on Common Stock	(187)	(187)			(187)
Shares issued:
Exercise of stock options, shares			792,288
Exercise of stock options	26	26		26
Restricted stock awards, shares			232,250
Restricted stock awards	0	0		0
Other benefit plans, shares			75,381
Other benefit plans	7	7		7
Dividend reinvestment plan, shares			19,516
Dividend reinvestment plan	2	2		2
Stock-based compensation expense	13	13		13
Shares exchanged — benefit plans, shares			(32,509)
Shares exchanged — benefit plans	(3)	(3)		0	(3)
Forfeitures of restricted stock, shares			(4,073)
Forfeitures of restricted stock	0	0		0
Other	$ (5)						(5)
Ending Balance, shares at Jun. 30, 2017	88,007,252		88,007,252
Ending Balance at Jun. 30, 2017	$ 5,312	$ 5,312		$ 1,246	$ 3,451	$ 615	$ 0