Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2014

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, 2014	Ownership Interest		Property, Plant & Equipment		Accumulated Depreciation			Construction in Progress
(in millions, except percentages)
Freestone Energy Center	75.0	%	$	389	$	(140	)	$	—
Hidalgo Energy Center	78.5	%	$	257	$	(104	)	$	—

Schedule of Components of Restricted Cash

Certain of our debt agreements, lease agreements or other operating agreements require us to establish and maintain segregated cash accounts, the use of which is restricted. These amounts are held by depository banks in order to comply with the contractual provisions requiring reserves for payments such as for debt service, rent, major maintenance and debt repurchases or with applicable regulatory requirements. Funds that can be used to satisfy obligations due during the next 12 months are classified as current restricted cash, with the remainder classified as non-current restricted cash. Restricted cash is generally invested in accounts earning market rates; therefore, the carrying value approximates fair value. Such cash is excluded from cash and cash equivalents on our Consolidated Balance Sheets and Statements of Cash Flows.

The table below represents the components of our restricted cash as of December 31, 2014 and 2013 (in millions):

	2014						2013
	Current		Non-Current		Total		Current		Non-Current		Total
Debt service	$	10	$	25	$	35	$	11	$	41	$	52
Rent reserve	4		—		4		3		—		3
Construction/major maintenance	54		17		71		35		20		55
Security/project/insurance	127		5		132		151		6		157
Other	—		2		2		3		2		5
Total	$	195	$	49	$	244	$	203	$	69	$	272

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 at December 31, 2014, are as follows (in millions):

2015	$	561
2016	495
2017	433
2018	396
2019	357
Thereafter	1,380
Total	$	3,622

Future minimum rent payments under these lease agreements, including renewal options and rent escalation clauses, are as follows (in millions):

	Initial Year	2015		2016		2017		2018		2019		Thereafter		Total
Land and other operating leases	various	$	15	$	16	$	15	$	15	$	15	$	201	$	277
Power plant operating leases:
Greenleaf	1998	$	4	$	—	$	—	$	—	$	—	$	—	$	4
KIAC	2000	23		22		22		22		30		—		119
Total power plant leases		$	27	$	22	$	22	$	22	$	30	$	—	$	123
Total leases		$	42	$	38	$	37	$	37	$	45	$	201	$	400