Summary of Signification Accounting Policies, Investment Tax Credits, NMTC Fund, and Accounting for Renewable Energy Tax Credits (Details) (New Markets Tax Credit [Member])	12 Months Ended
	Dec. 31, 2014
New Markets Tax Credit [Member]
Other Commitments [Line Items]
Period of Recognition of Gross Investment Amortization Expense	9 years
Remaining Period of Recognition of Gross Investment Amortization Expense	3 years