Consolidated Statement of Equity Consolidated Statement of Equity - 9 months ended Sep. 30, 2016 - USD ($) $ in Millions	Total	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Common Stock [Member]	Non-Controlling Interest in Subsidiaries [Member]
Beginning Balance at Dec. 31, 2015	$ 1,822.4	$ 573.3	$ (24.5)	$ 1,271.4	$ 2.2
Comprehensive Income [Abstract]
Net Income	111.5	111.0			0.5
Other Comprehensive Income – Net of Tax [Abstract]
Unrealized Gain on Securities	0.3		0.3
Defined Benefit Pension and Other Postretirement Plans	0.5		0.5
Total Comprehensive Income	112.3
Common Stock Issued	30.0			30.0
Common Stock Retired	(8.0)			(8.0)
Dividends Declared	(77.0)	(77.0)
Acquisition of Non-Controlling Interest	(6.7)			(4.0)	(2.7)
Ending Balance at Sep. 30, 2016	$ 1,873.0	$ 607.3	$ (23.7)	$ 1,289.4	$ 0.0