SEGMENT INFORMATION (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,777,700,000	$ 1,892,600,000	$ 1,635,900,000	$ 1,995,000,000	$ 1,684,000,000	$ 1,861,500,000	$ 1,628,700,000	$ 1,099,600,000	$ 7,301,204,000	$ 6,273,787,000	$ 4,465,657,000
Operating Income	360,600,000	399,300,000	350,600,000	418,900,000	331,400,000	412,900,000	159,500,000	214,400,000	1,529,435,000	1,118,206,000	794,176,000
Total Interest Expense									(338,699,000)	(329,945,000)	(250,425,000)
Income Tax Expense									(426,941,000)	(274,926,000)	(170,953,000)
Net Income	179,200,000	211,400,000	173,100,000	230,000,000	176,600,000	209,500,000	46,200,000	100,800,000	793,689,000	533,077,000	400,513,000
Net Income Attributable to Noncontrolling Interests									(7,682,000)	(7,132,000)	(5,820,000)
Net Income Attributable to Controlling Interests	177,400,000	209,500,000	171,000,000	228,100,000	174,700,000	207,600,000	44,300,000	99,300,000	786,007,000	525,945,000	394,693,000
Total Assets	27,795,537,000				28,302,824,000				27,795,537,000	28,302,824,000
Investments in Property, Plant and Equipment									1,456,787,000	1,472,272,000	1,076,730,000
Electric Distribution Member
Segment Reporting Information [Line Items]
Operating Revenues									5,362,300,000	4,716,500,000	3,343,100,000
Depreciation And Amortization									(604,800,000)	(530,300,000)	(337,200,000)
Operating Expenses, Other									(3,927,700,000)	(3,585,400,000)	(2,637,400,000)
Operating Income									829,800,000	600,800,000	368,500,000
Total Interest Expense									(175,000,000)	(165,600,000)	(123,800,000)
Interest Income									4,100,000	2,800,000	3,700,000
Other Income/(Loss)									12,900,000	8,900,000	11,600,000
Income Tax Expense									(240,000,000)	(150,200,000)	(67,600,000)
Net Income									431,800,000	296,700,000	192,400,000
Net Income Attributable to Noncontrolling Interests									(4,800,000)	(4,400,000)	(3,300,000)
Net Income Attributable to Controlling Interests									427,000,000	292,300,000	189,100,000
Total Assets	17,260,000,000				18,047,300,000				17,260,000,000	18,047,300,000
Investments in Property, Plant and Equipment									639,000,000	611,700,000	540,700,000
Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Operating Revenues									855,800,000	572,900,000	430,800,000
Depreciation And Amortization									(66,700,000)	(49,100,000)	(27,700,000)
Operating Expenses, Other									(659,400,000)	(445,200,000)	(333,500,000)
Operating Income									129,700,000	78,600,000	69,600,000
Total Interest Expense									(33,100,000)	(31,300,000)	(21,000,000)
Interest Income									0	0	0
Other Income/(Loss)									800,000	400,000	1,300,000
Income Tax Expense									(36,500,000)	(16,900,000)	(18,200,000)
Net Income									60,900,000	30,800,000	31,700,000
Net Income Attributable to Noncontrolling Interests									0	0	0
Net Income Attributable to Controlling Interests									60,900,000	30,800,000	31,700,000
Total Assets	2,759,700,000				2,717,400,000				2,759,700,000	2,717,400,000
Investments in Property, Plant and Equipment									168,100,000	148,700,000	98,200,000
Transmission [Member]
Segment Reporting Information [Line Items]
Operating Revenues									978,700,000	861,500,000	635,400,000
Depreciation And Amortization									(136,200,000)	(109,200,000)	(84,000,000)
Operating Expenses, Other									(281,800,000)	(251,600,000)	(188,200,000)
Operating Income									560,700,000	500,700,000	363,200,000
Total Interest Expense									(100,300,000)	(96,700,000)	(76,700,000)
Interest Income									700,000	400,000	500,000
Other Income/(Loss)									10,900,000	7,300,000	10,700,000
Income Tax Expense									(182,100,000)	(159,200,000)	(95,600,000)
Net Income									289,900,000	252,500,000	202,100,000
Net Income Attributable to Noncontrolling Interests									(2,900,000)	(2,800,000)	(2,500,000)
Net Income Attributable to Controlling Interests									287,000,000	249,700,000	199,600,000
Total Assets	6,745,800,000				6,187,700,000				6,745,800,000	6,187,700,000
Investments in Property, Plant and Equipment									618,500,000	663,600,000	388,900,000
Other Segment [Member]
Segment Reporting Information [Line Items]
Operating Revenues									777,500,000	803,800,000	541,300,000
Depreciation And Amortization									(62,200,000)	(56,400,000)	(16,800,000)
Operating Expenses, Other									(715,000,000)	(817,000,000)	(534,100,000)
Operating Income									300,000	(69,600,000)	(9,600,000)
Total Interest Expense									(35,500,000)	(43,600,000)	(33,700,000)
Interest Income									5,400,000	7,100,000	5,300,000
Other Income/(Loss)									858,900,000	795,000,000	455,200,000
Income Tax Expense									31,900,000	55,500,000	14,300,000
Net Income									861,000,000	744,400,000	431,500,000
Net Income Attributable to Noncontrolling Interests									0	0	0
Net Income Attributable to Controlling Interests									861,000,000	744,400,000	431,500,000
Total Assets	11,842,400,000				18,832,600,000				11,842,400,000	18,832,600,000
Investments in Property, Plant and Equipment									31,200,000	48,300,000	48,900,000
Eliminations Segment [Member]
Segment Reporting Information [Line Items]
Operating Revenues									(673,100,000)	(680,900,000)	(484,900,000)
Depreciation And Amortization									10,200,000	4,200,000	2,500,000
Operating Expenses, Other									671,800,000	684,400,000	484,900,000
Operating Income									8,900,000	7,700,000	2,500,000
Total Interest Expense									5,200,000	7,300,000	4,800,000
Interest Income									(5,600,000)	(7,100,000)	(5,300,000)
Other Income/(Loss)									(858,200,000)	(795,100,000)	(455,300,000)
Income Tax Expense									(200,000)	(4,100,000)	(3,900,000)
Net Income									(849,900,000)	(791,300,000)	(457,200,000)
Net Income Attributable to Noncontrolling Interests									0	0	0
Net Income Attributable to Controlling Interests									(849,900,000)	(791,300,000)	(457,200,000)
Total Assets	(10,812,400,000)				(17,482,200,000)				(10,812,400,000)	(17,482,200,000)
Investments in Property, Plant and Equipment									0	0	0
Total [Member]
Segment Reporting Information [Line Items]
Operating Revenues									7,301,200,000	6,273,800,000	4,465,700,000
Depreciation And Amortization									(859,700,000)	(740,800,000)	(463,200,000)
Operating Expenses, Other									(4,912,100,000)	(4,414,800,000)	(3,208,300,000)
Operating Income									1,529,400,000	1,118,200,000	794,200,000
Total Interest Expense									(338,700,000)	(329,900,000)	(250,400,000)
Interest Income									4,600,000	3,200,000	4,200,000
Other Income/(Loss)									25,300,000	16,500,000	23,500,000
Income Tax Expense									(426,900,000)	(274,900,000)	(171,000,000)
Net Income									793,700,000	533,100,000	400,500,000
Net Income Attributable to Noncontrolling Interests									(7,700,000)	(7,200,000)	(5,800,000)
Net Income Attributable to Controlling Interests									786,000,000	525,900,000	394,700,000
Total Assets	27,795,500,000				28,302,800,000				27,795,500,000	28,302,800,000
Investments in Property, Plant and Equipment									$ 1,456,800,000	$ 1,472,300,000	$ 1,076,700,000