Income Taxes Tax-Advantaged Amortization (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Investments In Affordable Housing Projects [Abstract]
Tax Credits	$ 7.0	$ 7.6	$ 25.0	$ 21.3
Benefits from Tax losses	2.0	2.0	6.0	5.5
Amorization for tax-advantaged investments	6.7	7.2	22.8	19.6
Total tax-advantaged amounts recorded in income taxes	$ 2.3	$ 2.4	$ 8.2	$ 7.2