Regulatory Matters (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Jan. 02, 2014	Sep. 30, 2012	Jul. 30, 2012
Public Utilities, General Disclosures [Abstract]
Defer the Reversal of RDM Liability				$ 127
Monthly Amount to Amortize from Liability to Income			10.6
PSCR Under-Recovery from Two Plan Years Prior		87
PSCR under-recovery from Three Plan Years Prior		148
Fermi 2 Production Level of Full Capacity					68.00%
Maximum of challenged Fermi 2 outage charges	32
PSCR over-recovery from One Plan Year Prior	$ 54