Historic Tax Credits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended			12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2013
Equity contribution by counterparty [Line Items]
Other Income	$ 1.8	$ 1.8		$ 1.8
First Stage [Member]
Equity contribution by counterparty [Line Items]
Payments for Repurchase of Other Equity					$ 5.8	$ 5.5
Fourth recapture of the third stage [Member]
Equity contribution by counterparty [Line Items]
Other Income	0.9		$ 0.9
Third recapture of the first stage [Member] [Member]
Equity contribution by counterparty [Line Items]
Other Income				0.9
Third recapture of the second stage [Member]
Equity contribution by counterparty [Line Items]
Other Income	1.0		1.0
Second recapture of the second stage [Member]
Equity contribution by counterparty [Line Items]
Other Income		0.9		0.9
Priority Returns earned by counterparty [Member]
Equity contribution by counterparty [Line Items]
Other Expenses	$ 0.2	$ 0.3	$ 0.3	$ 0.3