SEGMENT INFORMATION (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,677,614,000	$ 1,635,862,000	$ 3,968,204,000	$ 3,630,885,000
Operating Income	293,990,000	350,576,000	761,679,000	769,521,000
Total Interest Expense	(92,495,000)	(86,850,000)	(182,471,000)	(163,106,000)
Other Income/(Loss), Net	5,526,000	4,944,000	7,194,000	12,710,000
Income Tax Expense	(77,774,000)	(95,606,000)	(219,319,000)	(216,093,000)
Net Income	129,247,000	173,064,000	367,083,000	403,032,000
Net Income Attributable to Noncontrolling Interests	(1,880,000)	(2,043,000)	(3,759,000)	(3,922,000)
Net Income Attributable to Controlling Interests	127,367,000	171,021,000	363,324,000	399,110,000
Total Assets	27,790,445,000		27,790,445,000		27,795,537,000
Investments in Property, Plant and Equipment			724,043,000	700,252,000
Electric Distribution Member
Segment Reporting Information [Line Items]
Operating Revenues	1,261,800,000	1,221,600,000	2,847,800,000	2,595,800,000
Depreciation And Amortization	(89,300,000)	(152,200,000)	(238,200,000)	(329,100,000)
Operating Expenses, Other	(991,500,000)	(883,300,000)	(2,202,400,000)	(1,888,300,000)
Operating Income	181,000,000	186,100,000	407,200,000	378,400,000
Total Interest Expense	(47,200,000)	(43,400,000)	(94,600,000)	(85,600,000)
Other Income/(Loss), Net	2,900,000	2,200,000	4,300,000	7,100,000
Net Income Attributable to Controlling Interests	83,400,000	91,200,000	195,600,000	190,600,000
Total Assets	16,942,500,000		16,942,500,000		17,260,000,000
Investments in Property, Plant and Equipment			335,600,000	315,300,000
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Operating Revenues	195,500,000	154,100,000	628,300,000	515,900,000
Depreciation And Amortization	(16,900,000)	(16,700,000)	(34,600,000)	(34,100,000)
Operating Expenses, Other	(166,500,000)	(127,000,000)	(487,900,000)	(394,300,000)
Operating Income	12,100,000	10,400,000	105,800,000	87,500,000
Total Interest Expense	(8,700,000)	(8,900,000)	(17,100,000)	(16,200,000)
Other Income/(Loss), Net	0	100,000	100,000	300,000
Net Income Attributable to Controlling Interests	2,000,000	1,200,000	54,100,000	44,500,000
Total Assets	2,753,800,000		2,753,800,000		2,759,700,000
Investments in Property, Plant and Equipment			68,600,000	70,900,000
Transmission [Member]
Segment Reporting Information [Line Items]
Operating Revenues	206,900,000	247,900,000	458,900,000	487,400,000
Depreciation And Amortization	(37,000,000)	(34,500,000)	(74,000,000)	(66,300,000)
Operating Expenses, Other	(71,000,000)	(63,600,000)	(137,300,000)	(125,800,000)
Operating Income	98,900,000	149,800,000	247,600,000	295,300,000
Total Interest Expense	(28,800,000)	(25,200,000)	(54,300,000)	(47,100,000)
Other Income/(Loss), Net	2,700,000	2,800,000	4,200,000	5,500,000
Net Income Attributable to Controlling Interests	43,900,000	76,800,000	118,800,000	156,700,000
Total Assets	6,934,100,000		6,934,100,000		6,745,800,000
Investments in Property, Plant and Equipment			289,300,000	297,400,000
Other Segment [Member]
Segment Reporting Information [Line Items]
Operating Revenues	184,700,000	220,700,000	356,900,000	437,800,000
Depreciation And Amortization	(7,700,000)	(21,700,000)	(14,700,000)	(40,800,000)
Operating Expenses, Other	(174,900,000)	(194,900,000)	(340,300,000)	(392,200,000)
Operating Income	2,100,000	4,100,000	1,900,000	4,800,000
Total Interest Expense	(9,100,000)	(10,700,000)	(18,700,000)	(17,100,000)
Other Income/(Loss), Net	137,700,000	232,200,000	432,400,000	554,000,000
Net Income Attributable to Controlling Interests	133,300,000	232,800,000	424,900,000	555,500,000
Total Assets	11,566,600,000		11,566,600,000		11,842,400,000
Investments in Property, Plant and Equipment			30,500,000	16,700,000
Eliminations Segment [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(171,300,000)	(208,400,000)	(323,700,000)	(406,000,000)
Depreciation And Amortization	2,300,000	2,900,000	4,100,000	4,600,000
Operating Expenses, Other	168,900,000	205,700,000	318,800,000	404,900,000
Operating Income	(100,000)	200,000	(800,000)	3,500,000
Total Interest Expense	1,300,000	1,300,000	2,200,000	2,900,000
Other Income/(Loss), Net	(137,800,000)	(232,300,000)	(433,800,000)	(554,200,000)
Net Income Attributable to Controlling Interests	(135,200,000)	(231,000,000)	(430,100,000)	(548,200,000)
Total Assets	(10,406,600,000)		(10,406,600,000)		(10,812,400,000)
Investments in Property, Plant and Equipment			0	0
Total [Member]
Segment Reporting Information [Line Items]
Operating Revenues	1,677,600,000	1,635,900,000	3,968,200,000	3,630,900,000
Depreciation And Amortization	(148,600,000)	(222,200,000)	(357,400,000)	(465,700,000)
Operating Expenses, Other	(1,235,000,000)	(1,063,100,000)	(2,849,100,000)	(2,395,700,000)
Operating Income	294,000,000	350,600,000	761,700,000	769,500,000
Total Interest Expense	(92,500,000)	(86,900,000)	(182,500,000)	(163,100,000)
Other Income/(Loss), Net	5,500,000	5,000,000	7,200,000	12,700,000
Net Income Attributable to Controlling Interests	127,400,000	171,000,000	363,300,000	399,100,000
Total Assets	27,790,400,000		27,790,400,000		27,795,500,000
Investments in Property, Plant and Equipment			$ 724,000,000	$ 700,300,000