Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Summary of Significant Accounting Policies [Abstract]

Schedule of Jointly Owned Utility Plants [Table Text Block]

Jointly-Owned Plants — Certain of our subsidiaries own undivided interests in jointly-owned plants. These plants are maintained and operated pursuant to their joint ownership participation and operating agreements. We are responsible for our subsidiaries’ share of operating costs and direct expenses and include our proportionate share of the facilities and related revenues and direct expenses in these jointly-owned plants in the corresponding balance sheet and income statement captions of our Consolidated Financial Statements. The following table summarizes our proportionate ownership interest in jointly-owned power plants:

As of December 31, 2012	Ownership Interest		Property, Plant & Equipment		Accumulated Depreciation			Construction in Progress
(in millions, except percentages)
Freestone Energy Center	75.0	%	$	392	$	(124	)	$	1
Hidalgo Energy Center	78.5	%	$	252	$	(86	)	$	—

Schedule of Components of Restricted Cash

The table below represents the components of our restricted cash as of December 31, 2012 and 2011 (in millions):

	2012						2011
	Current		Non-Current		Total		Current		Non-Current		Total
Debt service(1)	$	11	$	41	$	52	$	11	$	42	$	53
Construction/major maintenance	32		14		46		33		10		43
Security/project/insurance	101		3		104		79		—		79
Other	49		2		51		16		3		19
Total	$	193	$	60	$	253	$	139	$	55	$	194

___________

(1) At both December 31, 2012 and 2011, amounts restricted for debt service included approximately $25 million of repurchase agreements with a financial institution containing maturity dates greater than one year.

Schedule of Total Contractual Future Minimum Lease Receipts

Leases — We have contracts, such as certain tolling agreements, which we account for as operating leases under U.S. GAAP. Generally, we levelize certain components of these contract revenues on a straight-line basis over the term of the contract. The total contractual future minimum lease rentals for our contracts accounted for as operating leases, excluding tolling agreements related to power plants under construction, at December 31, 2012, are as follows (in millions):

2013	$	548
2014	446
2015	455
2016	397
2017	359
Thereafter	2,078
Total	$	4,283

Future minimum lease payments under these leases are as follows (in millions):

	Initial Year	2013		2014		2015		2016		2017		Thereafter		Total
Land and other operating leases	various	$	14	$	14	$	14	$	15	$	15	$	228	$	300
Power plant operating leases:
Greenleaf	1998	$	7	$	3	$	—	$	—	$	—	$	—	$	10
KIAC	2000	24		24		23		22		22		52		167
Total power plant leases		$	31	$	27	$	23	$	22	$	22	$	52	$	177
Total leases		$	45	$	41	$	37	$	37	$	37	$	280	$	477