Investments Low Income Housing Tax Credits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Investments, All Other Investments [Abstract]
Low Income Housing Tax Credits	$ 10.5	$ 10.4	$ 20.9	$ 20.9
Amortization of Low Income Housing Investments	(5.8)	(5.8)	(11.6)	(11.6)
Tax Benefits from Low Income Housing Investments	$ 4.7	$ 4.6	$ 9.3	$ 9.3