Consolidated Statements of Equity (Unaudited) - USD ($)	Total	Preferred Stock	Common Stock	Capital in Excess of Par Value	Treasury Stock	Cumulative Net Income	Cumulative Dividends	Accumulated Other Comprehensive Income (Loss)	Other Equity	Noncontrolling Interests
Balances at beginning of period at Dec. 31, 2013	$ 11,756,331,000	$ 1,017,361,000	$ 289,461,000	$ 12,418,520,000	$ (21,263,000)	$ 2,329,869,000	$ (4,600,854,000)	$ (24,531,000)	$ 6,020,000	$ 341,748,000
Comprehensive income:
Net income (loss)	153,205,000					154,556,000				(1,351,000)
Other comprehensive income	4,481,000							5,889,000		(1,408,000)
Total comprehensive income	157,686,000
Net change in noncontrolling interests	(11,548,000)			(4,680,000)						(6,868,000)
Amounts related to issuance of common stock from dividend reinvestment and stock incentive plans, net of forfeitures	138,701,000		2,561,000	147,486,000	(11,026,000)				(320,000)
Proceeds from issuance of common stock	968,517,000		16,100,000	952,417,000
Conversion of preferred stock		(11,111,000)	233,000	10,878,000
Equity component of convertible debt	0
Option compensation expense	459,000								459,000
Cash dividends paid:
Common stock cash dividends	(462,551,000)						(462,551,000)
Preferred stock cash dividends	(32,705,000)						(32,705,000)
Balances at end of period at Jun. 30, 2014	12,514,890,000	1,006,250,000	308,355,000	13,524,621,000	(32,289,000)	2,484,425,000	(5,096,110,000)	(18,642,000)	6,159,000	332,121,000
Balances at beginning of period at Dec. 31, 2014	13,473,049,000	1,006,250,000	328,835,000	14,740,712,000	(35,241,000)	2,842,022,000	(5,635,923,000)	(77,009,000)	5,507,000	297,896,000
Comprehensive income:
Net income (loss)	540,049,000					536,074,000				3,975,000
Other comprehensive income	(13,610,000)							(4,661,000)		(8,949,000)
Total comprehensive income	526,439,000
Net change in noncontrolling interests	62,398,000			(2,786,000)						65,184,000
Amounts related to issuance of common stock from dividend reinvestment and stock incentive plans, net of forfeitures	148,479,000		2,189,000	154,463,000	(6,452,000)				(1,721,000)
Proceeds from issuance of common stock	1,423,264,000		19,550,000	1,403,714,000
Conversion of preferred stock	0
Equity component of convertible debt	5,815,000		1,077,000	4,738,000
Option compensation expense	452,000								452,000
Cash dividends paid:
Common stock cash dividends	(561,914,000)						(561,914,000)
Preferred stock cash dividends	(32,703,000)						(32,703,000)
Balances at end of period at Jun. 30, 2015	$ 15,045,279,000	$ 1,006,250,000	$ 351,651,000	$ 16,300,841,000	$ (41,693,000)	$ 3,378,096,000	$ (6,230,540,000)	$ (81,670,000)	$ 4,238,000	$ 358,106,000