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, 2012	$ 10,520,519,000	$ 1,022,917,000	$ 260,396,000	$ 10,543,690,000	$ (17,875,000)	$ 2,184,819,000	$ (3,694,579,000)	$ (11,028,000)	$ 6,461,000	$ 225,718,000
Comprehensive income:
Net income (loss)	114,705,000					117,050,000				(2,345,000)
Other comprehensive income	(17,094,000)							(12,447,000)		(4,647,000)
Total comprehensive income	97,611,000
Net change in noncontrolling interests	159,749,000		1,109,000	23,410,000						135,230,000
Amounts related to issuance of common stock from dividend reinvestment and stock incentive plans, net of forfeitures	174,760,000		2,756,000	176,840,000	(3,388,000)				(1,448,000)
Proceeds from issuance of common stock	1,630,281,000		23,000,000	1,607,281,000
Equity component of convertible debt	(555,000)		988,000	(1,543,000)
Option compensation expense	851,000								851,000
Cash dividends paid:
Common stock cash dividends	(618,992,000)						(618,992,000)
Preferred stock cash dividends	(49,805,000)						(49,805,000)
Balances at end of period at Sep. 30, 2013	11,914,419,000	1,022,917,000	288,249,000	12,349,678,000	(21,263,000)	2,301,869,000	(4,363,376,000)	(23,475,000)	5,864,000	353,956,000
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)	305,846,000					307,164,000				(1,318,000)
Other comprehensive income	(37,728,000)							(28,173,000)		(9,555,000)
Total comprehensive income	268,118,000
Net change in noncontrolling interests	(28,880,000)			(7,818,000)						(21,062,000)
Amounts related to issuance of common stock from dividend reinvestment and stock incentive plans, net of forfeitures	201,868,000		3,614,000	212,718,000	(13,978,000)				(486,000)
Proceeds from issuance of common stock	2,064,401,000		33,925,000	2,030,476,000
Conversion of preferred stock	0	(11,111,000)	233,000	10,878,000
Equity component of convertible debt	875,000		200,000	675,000
Option compensation expense	689,000								689,000
Cash dividends paid:
Common stock cash dividends	(708,923,000)						(708,923,000)
Preferred stock cash dividends	(49,057,000)						(49,057,000)
Balances at end of period at Sep. 30, 2014	$ 13,505,422,000	$ 1,006,250,000	$ 327,433,000	$ 14,665,449,000	$ (35,241,000)	$ 2,637,033,000	$ (5,358,834,000)	$ (52,704,000)	$ 6,223,000	$ 309,813,000