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, 2009	$ 3,807,451,000		$ 288,683,000	$ 123,385,000	$ 3,900,666,000	$ (7,619,000)	$ 1,547,669,000	$ (2,057,658,000)	$ (2,891,000)	$ 4,804,000	$ 10,412,000
Comprehensive income:
Net income (loss)	82,758,000						82,451,000				307,000
Other comprehensive income:
Unrealized gain (loss) on equity investments	(137,000)								(137,000)
Cash flow hedge activity	(5,498,000)								(5,498,000)
Total comprehensive income	77,123,000
Contributions by noncontrolling interests	2,271,000										2,271,000
Distributions to noncontrolling interests	(2,594,000)										(2,594,000)
Amounts related to issuance of common stock from dividend reinvestment and stock incentive plans, net of forfeitures	41,431,000			1,080,000	44,290,000	(3,696,000)				(243,000)
Conversion of preferred stock			(2,273,000)	55,000	2,218,000
Equity component of convertible debt	(9,689,000)				(9,689,000)
Option compensation expense	1,194,000									1,194,000
Cash dividends paid:
Common stock cash dividends	(169,069,000)							(169,069,000)
Preferred stock cash dividends	(10,993,000)							(10,993,000)
Balances at end of period at Jun. 30, 2010	3,737,125,000		286,410,000	124,520,000	3,937,485,000	(11,315,000)	1,630,120,000	(2,237,720,000)	(8,526,000)	5,755,000	10,396,000
Balances at beginning of period at Dec. 31, 2010	4,733,100,000	[1]	291,667,000	147,155,000	4,932,468,000	(11,352,000)	1,676,196,000	(2,427,881,000)	(11,099,000)	5,697,000	130,249,000
Comprehensive income:
Net income (loss)	117,856,000						119,252,000				(1,396,000)
Other comprehensive income:
Unrealized gain (loss) on equity investments	86,000								86,000
Cash flow hedge activity	868,000								868,000
Total comprehensive income	118,810,000
Contributions by noncontrolling interests	28,243,000				6,017,000						22,226,000
Distributions to noncontrolling interests	(16,227,000)										(16,227,000)
Amounts related to issuance of common stock from dividend reinvestment and stock incentive plans, net of forfeitures	67,880,000			1,385,000	69,524,000	(2,141,000)				(888,000)
Proceeds from issuance of common stock	1,357,746,000			28,750,000	1,328,996,000
Proceeds from issuance of preferred stock	696,437,000		718,750,000		(22,313,000)
Option compensation expense	1,651,000									1,651,000
Cash dividends paid:
Common stock cash dividends	(228,565,000)							(228,565,000)
Preferred stock cash dividends	(26,033,000)							(26,033,000)
Balances at end of period at Jun. 30, 2011	6,733,042,000		1,010,417,000	177,290,000	6,314,692,000	(13,493,000)	1,795,448,000	(2,682,479,000)	(10,145,000)	6,460,000	134,852,000
Balances at beginning of period at Mar. 31, 2011
Other comprehensive income:
Unrealized gain (loss) on equity investments	(236,000)
Cash flow hedge activity	386,000
Option compensation expense										612,000
Balances at end of period at Jun. 30, 2011	$ 6,733,042,000									$ 6,460,000

[1] NOTE: The consolidated balance sheet at December 31, 2010 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements.