Financing Receivables (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Lease investment with non-investment grade counterparties, gross	$ 563
Lease investment with non-investment grade counterparties, net of deferred taxes	13
NRG commitment to invest	$ 350
Powerton Station [Member]
Lease Receivable Percent Owned	64.00%