Investments Low Income Housing Tax Credits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investments, All Other Investments [Abstract]
Low Income Housing Tax Credits	$ 10.3	$ 10.5	$ 20.7	$ 20.9
Amortization of Low Income Housing Investments	(7.0)	(5.8)	(14.0)	(11.6)
Tax Benefits from Low Income Housing Investments	$ 3.3	$ 4.7	$ 6.7	$ 9.3