SEGMENT INFORMATION (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,892,532,000	$ 1,892,590,000	$ 5,860,736,000	$ 5,523,475,000
Operating Income	440,910,000	399,262,000	1,202,588,000	1,168,783,000
Total Interest Expense	(89,738,000)	(87,476,000)	(272,208,000)	(250,583,000)
Other Income/(Loss), Net	11,860,000	8,945,000	19,054,000	21,655,000
Income Tax Expense	(126,539,000)	(109,351,000)	(345,858,000)	(325,442,000)
Net Income	236,493,000	211,380,000	603,576,000	614,413,000
Net Income Attributable to Noncontrolling Interests	(1,879,000)	(1,879,000)	(5,639,000)	(5,803,000)
Net Income Attributable to Controlling Interests	234,614,000	209,501,000	597,937,000	608,610,000
Total Assets	27,982,311,000		27,982,311,000		27,795,537,000
Investments in Property, Plant and Equipment			1,117,493,000	1,073,759,000
Electric Distribution Member
Segment Reporting Information [Line Items]
Operating Revenues	1,502,600,000	1,508,600,000	4,350,400,000	4,104,400,000
Depreciation And Amortization	(71,700,000)	(159,600,000)	(309,900,000)	(488,700,000)
Operating Expenses, Other	(1,141,500,000)	(1,064,100,000)	(3,343,900,000)	(2,952,400,000)
Operating Income	289,400,000	284,900,000	696,600,000	663,300,000
Total Interest Expense	(49,200,000)	(44,300,000)	(143,800,000)	(129,900,000)
Other Income/(Loss), Net	9,300,000	5,500,000	13,600,000	12,600,000
Net Income Attributable to Controlling Interests	153,400,000	156,900,000	349,100,000	347,500,000
Total Assets	16,702,300,000		16,702,300,000		17,260,000,000
Investments in Property, Plant and Equipment			480,100,000	501,900,000
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Operating Revenues	109,200,000	97,100,000	737,500,000	613,000,000
Depreciation And Amortization	(16,400,000)	(16,400,000)	(51,100,000)	(50,500,000)
Operating Expenses, Other	(98,400,000)	(89,400,000)	(586,200,000)	(483,600,000)
Operating Income	(5,600,000)	(8,700,000)	100,200,000	78,900,000
Total Interest Expense	(8,500,000)	(8,600,000)	(25,600,000)	(24,800,000)
Other Income/(Loss), Net	100,000	500,000	200,000	700,000
Net Income Attributable to Controlling Interests	(9,900,000)	(10,400,000)	44,200,000	34,100,000
Total Assets	2,801,100,000		2,801,100,000		2,759,700,000
Investments in Property, Plant and Equipment			120,600,000	91,200,000
Transmission [Member]
Segment Reporting Information [Line Items]
Operating Revenues	262,500,000	234,100,000	721,400,000	721,500,000
Depreciation And Amortization	(37,400,000)	(34,500,000)	(111,400,000)	(100,900,000)
Operating Expenses, Other	(74,200,000)	(73,400,000)	(211,500,000)	(199,100,000)
Operating Income	150,900,000	126,200,000	398,500,000	421,500,000
Total Interest Expense	(24,500,000)	(26,600,000)	(78,800,000)	(73,700,000)
Other Income/(Loss), Net	2,700,000	2,900,000	6,900,000	8,500,000
Net Income Attributable to Controlling Interests	88,100,000	58,600,000	206,800,000	215,400,000
Total Assets	7,404,500,000		7,404,500,000		6,745,800,000
Investments in Property, Plant and Equipment			469,900,000	458,200,000
Other Segment [Member]
Segment Reporting Information [Line Items]
Operating Revenues	211,200,000	212,500,000	568,100,000	650,400,000
Depreciation And Amortization	(13,800,000)	(11,200,000)	(28,300,000)	(52,000,000)
Operating Expenses, Other	(192,400,000)	(206,800,000)	(534,100,000)	(599,000,000)
Operating Income	5,000,000	(5,500,000)	5,700,000	(600,000)
Total Interest Expense	(8,600,000)	(9,200,000)	(27,200,000)	(26,300,000)
Other Income/(Loss), Net	226,400,000	312,100,000	657,900,000	866,200,000
Net Income Attributable to Controlling Interests	228,300,000	313,100,000	653,400,000	868,700,000
Total Assets	12,270,200,000		12,270,200,000		11,842,400,000
Investments in Property, Plant and Equipment			46,900,000	22,500,000
Eliminations Segment [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(193,000,000)	(159,700,000)	(516,700,000)	(565,800,000)
Depreciation And Amortization	8,600,000	2,600,000	12,700,000	7,200,000
Operating Expenses, Other	185,600,000	159,500,000	505,600,000	564,300,000
Operating Income	1,200,000	2,400,000	1,600,000	5,700,000
Total Interest Expense	1,000,000	1,200,000	3,200,000	4,100,000
Other Income/(Loss), Net	(226,600,000)	(312,100,000)	(659,500,000)	(866,300,000)
Net Income Attributable to Controlling Interests	(225,300,000)	(308,700,000)	(655,600,000)	(857,100,000)
Total Assets	(11,195,800,000)		(11,195,800,000)		(10,812,400,000)
Investments in Property, Plant and Equipment			0	0
Total [Member]
Segment Reporting Information [Line Items]
Operating Revenues	1,892,500,000	1,892,600,000	5,860,700,000	5,523,500,000
Depreciation And Amortization	(130,700,000)	(219,100,000)	(488,000,000)	(684,900,000)
Operating Expenses, Other	(1,320,900,000)	(1,274,200,000)	(4,170,100,000)	(3,669,800,000)
Operating Income	440,900,000	399,300,000	1,202,600,000	1,168,800,000
Total Interest Expense	(89,800,000)	(87,500,000)	(272,200,000)	(250,600,000)
Other Income/(Loss), Net	11,900,000	8,900,000	19,100,000	21,700,000
Net Income Attributable to Controlling Interests	234,600,000	209,500,000	597,900,000	608,600,000
Total Assets	27,982,300,000		27,982,300,000		27,795,500,000
Investments in Property, Plant and Equipment			$ 1,117,500,000	$ 1,073,800,000