Consolidated Statements of Changes in Equity (Details) (USD $)	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period	$ 11,086,000,000		$ 11,494,000,000
Net income (loss)	114,000,000		214,000,000
Other comprehensive loss	21,000,000		(1,000,000)
Contributions from noncontrolling interests	238,000,000	[1]
Transfer of assets to Capistrano Wind Partners	(50,000,000)	[2]
Common stock dividends declared ($0.325 and $0.32 per share, 2012 and 2011 respectively)	(106,000,000)		(104,000,000)
Dividends, distributions to noncontrolling interests and other	(18,000,000)		(15,000,000)
Stock-based compensation and other	(28,000,000)		(7,000,000)
Noncash stock-based compensation and other	5,000,000		5,000,000
Issuance of preference stock	345,000,000		123,000,000
Balance, at the end of the period	11,607,000,000		11,709,000,000
Reduction to additional paid in capital, related to new tax basis in assets transferred	(50,000,000)	[2]
Dividends declared per common share (in dollars per share)	$ 0.325		$ 0.32
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period	2,360,000,000		2,331,000,000
Net income (loss)	0		0
Other comprehensive loss	0		0
Contributions from noncontrolling interests	0	[1]
Transfer of assets to Capistrano Wind Partners	(50,000,000)	[2]
Common stock dividends declared ($0.325 and $0.32 per share, 2012 and 2011 respectively)	0		0
Dividends, distributions to noncontrolling interests and other	0		0
Stock-based compensation and other	8,000,000		2,000,000
Noncash stock-based compensation and other	7,000,000		7,000,000
Issuance of preference stock	0		0
Balance, at the end of the period	2,325,000,000		2,340,000,000
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period	(139,000,000)		(76,000,000)
Net income (loss)	0		0
Other comprehensive loss	21,000,000		(1,000,000)
Contributions from noncontrolling interests	0	[1]
Transfer of assets to Capistrano Wind Partners	0	[2]
Common stock dividends declared ($0.325 and $0.32 per share, 2012 and 2011 respectively)	0		0
Dividends, distributions to noncontrolling interests and other	0		0
Stock-based compensation and other	0		0
Noncash stock-based compensation and other	0		0
Issuance of preference stock	0		0
Balance, at the end of the period	(118,000,000)		(77,000,000)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period	7,834,000,000		8,328,000,000
Net income (loss)	93,000,000		200,000,000
Other comprehensive loss	0		0
Contributions from noncontrolling interests	0	[1]
Transfer of assets to Capistrano Wind Partners	0	[2]
Common stock dividends declared ($0.325 and $0.32 per share, 2012 and 2011 respectively)	(106,000,000)		(104,000,000)
Dividends, distributions to noncontrolling interests and other	0		0
Stock-based compensation and other	(36,000,000)		(9,000,000)
Noncash stock-based compensation and other	(2,000,000)		(2,000,000)
Issuance of preference stock	0		0
Balance, at the end of the period	7,783,000,000		8,413,000,000
Subtotal
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period	10,055,000,000		10,583,000,000
Net income (loss)	93,000,000		200,000,000
Other comprehensive loss	21,000,000		(1,000,000)
Contributions from noncontrolling interests	0	[1]
Transfer of assets to Capistrano Wind Partners	(50,000,000)	[2]
Common stock dividends declared ($0.325 and $0.32 per share, 2012 and 2011 respectively)	(106,000,000)		(104,000,000)
Dividends, distributions to noncontrolling interests and other	0		0
Stock-based compensation and other	(28,000,000)		(7,000,000)
Noncash stock-based compensation and other	5,000,000		5,000,000
Issuance of preference stock	0		0
Balance, at the end of the period	9,990,000,000		10,676,000,000
Other
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period	2,000,000		4,000,000
Net income (loss)	2,000,000		0
Other comprehensive loss	0		0
Contributions from noncontrolling interests	238,000,000	[1]
Transfer of assets to Capistrano Wind Partners	0	[2]
Common stock dividends declared ($0.325 and $0.32 per share, 2012 and 2011 respectively)	0		0
Dividends, distributions to noncontrolling interests and other	1,000,000		(1,000,000)
Stock-based compensation and other	0		0
Noncash stock-based compensation and other	0		0
Issuance of preference stock	0		0
Balance, at the end of the period	243,000,000		3,000,000
Preferred Stock and Preference Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, at the beginning of the period	1,029,000,000		907,000,000
Net income (loss)	19,000,000		14,000,000
Other comprehensive loss	0		0
Contributions from noncontrolling interests	0	[1]
Transfer of assets to Capistrano Wind Partners	0	[2]
Common stock dividends declared ($0.325 and $0.32 per share, 2012 and 2011 respectively)	0		0
Dividends, distributions to noncontrolling interests and other	(19,000,000)		(14,000,000)
Stock-based compensation and other	0		0
Noncash stock-based compensation and other	0		0
Issuance of preference stock	345,000,000		123,000,000
Balance, at the end of the period	$ 1,374,000,000		$ 1,030,000,000

[1] Funds contribution by third-party investors related to the Capistrano Wind equity capital raise are reported in noncontrolling interest. For further information, see Note 3.

[2] Additional paid in capital was reduced $50 million related to a new tax basis in the assets transferred to Capistrano Wind Partners. For further information, see Note 3.The follow