Financing Receivables (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	0 Months Ended	12 Months Ended				0 Months Ended	3 Months Ended
	Dec. 13, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Energy Holdings [Member]	Oct. 02, 2012 Subsequent Event [Member]	Dec. 31, 2012 Subsequent Event [Member]
Net Investments in Leases			$ 117	$ 165
Lease investment with non-investment grade counterparties, gross					559
Lease investment with non-investment grade counterparties, net of deferred taxes					19
Scheduled rent payables			48
Partial Rental Payment		5
Cash payment of lease	7.5
Claim payable	110
Write off of gross lease investment			264
Total recovery of Energy Holdings' indirect subsidiary companies from Dynegy leases						63
Remaining recovery recorded in Operating Revenues in the fourth quarter 2012							$ 50