Condensed Financial Information Of Registrant (Statement Of Income) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity in net earnings of consolidated subsidiaries									$ 46.6	$ 35.9	$ 32.2
Interest expense									(443.6)	(414.8)	(418.3)
Other, net									22.3	24.2	1.7
Total Other income (deductions)									(421.3)	(390.6)	(416.6)
Income from continuing operations before income taxes									841.1	752.8	623.5
Income taxes									310.4	261.9	214.7
Income from continuing operations	154.3	31.5	78.5	266.4	153.0	49.5	72.4	216.0	530.7	490.9	408.8
(Loss) Income from Discontinued Operations - net of taxes	(0.1)	(0.1)	(0.3)	(0.2)	(1.2)	(1.4)	(0.7)	44.5	(0.7)	6.3	7.3
Gain (Loss) on Disposition of Discontinued Operations - net of taxes									0	34.9	0
Net Income (Loss) Attributable to Parent	154.2	31.4	78.2	266.2	151.8	48.1	71.7	260.5	530.0	532.1	416.1
Basic Earnings (Loss) Per Share, Continuing Operations	$ 0.49	$ 0.10	$ 0.25	$ 0.85	$ 0.49	$ 0.16	$ 0.23	$ 0.69
Discontinued operations	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.01)	$ 0.00	$ 0.00	$ 0.14
Basic Earnings (Loss) Per Share	$ 0.49	$ 0.10	$ 0.25	$ 0.85	$ 0.48	$ 0.16	$ 0.23	$ 0.83	$ 1.68	$ 1.70	$ 1.43
Continuing operations	$ 0.49	$ 0.10	$ 0.25	$ 0.85	$ 0.49	$ 0.16	$ 0.23	$ 0.69
Discontinued operations	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.01)	$ 0.00	$ 0.00	$ 0.14
Diluted earnings per share	$ 0.49	$ 0.10	$ 0.25	$ 0.85	$ 0.48	$ 0.16	$ 0.23	$ 0.83	$ 1.67	$ 1.70	$ 1.39
Parent Company [Member]
Equity in net earnings of consolidated subsidiaries									671.7	621.6	546.1
Administrative and general expenses									(49.5)	(11.6)	(2.9)
Interest income									1.7	3.8	4.6
Interest expense									(198.4)	(209.5)	(227.6)
Other, net									(5.0)	(5.0)	(10.0)
Total Other income (deductions)									(251.2)	(222.3)	(235.9)
Income from continuing operations before income taxes									420.5	399.3	310.2
Income taxes									(110.2)	(91.6)	(98.6)
Income from continuing operations									530.7	490.9	408.8
(Loss) Income from Discontinued Operations - net of taxes									(0.7)	6.3	7.3
Gain (Loss) on Disposition of Discontinued Operations - net of taxes									0	34.9	0
Net Income (Loss) Attributable to Parent									$ 530.0	$ 532.1	$ 416.1
Average common shares outstanding									315,120	312,402	291,927
Diluted average common shares									316,636	313,646	300,401
Basic Earnings (Loss) Per Share, Continuing Operations									$ 1.68	$ 1.57	$ 1.40
Discontinued operations									$ 0.00	$ 0.13	$ 0.03
Basic Earnings (Loss) Per Share									$ 1.68	$ 1.70
Continuing operations									$ 1.67	$ 1.57	$ 1.36
Discontinued operations									$ 0.00	$ 0.13	$ 0.03
Diluted earnings per share									$ 1.67	$ 1.70	$ 1.39