Short-Term Debt and Credit Facilities (Details) (USD $) In Millions, unless otherwise specified			9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Og and E [Member]	Sep. 30, 2013 Maximum [Member]
Short-term Debt [Line Items]
Advances from parent	$ 47.6	$ 0
Advances to parent	0	90.3
Intercomany Borrowings, Maximum Borrowing Capacity			400.0
Intercompany Borrowing Agreement, Expiration Date			Dec. 13, 2017
Outstanding Intercompany Borrowings			0
Aggregate Commitment - Revolving Credit Facility			400.0
Weighted Average Interest Rate			0.53%
Outstanding borrowings under revolving credit agreement			2.1
Cash				0.1
Short Term Borrowing Capacity That Has Regulatory Approval			$ 800
Period For Which Regulatory Approval Has Been Given to Acquire Short Term Debt			2 years