Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2016

Balance Sheet Components [Abstract]

Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]

The following is the activity in the allowance for uncollectible accounts (in millions):

	Years Ended December 31,
	2016			2015			2014
Balance as of beginning of year	$	6		$	6		$	6
Increase in provision	5			6			6
Amounts written off, less recoveries	(5		)	(6		)	(6		)
Balance as of end of year	$	6		$	6		$	6

Investments held in trust [Table Text Block]

The trusts are comprised of the following investments as of December 31 (in millions):

	Nuclear     Decommissioning Trust				Non-Qualified Benefit     Plan Trust
	2016		2015		2016		2015
Cash equivalents	$	21	$	18	$	1	$	1
Marketable securities, at fair value:
Equity securities	—		—		6		5
Debt securities	20		22		1		1
Insurance contracts, at cash surrender value	—		—		26		26
	$	41	$	40	$	34	$	33

Schedule of Other Assets and Other Liabilities [Table Text Block]

Other current assets and Accrued expenses and other current liabilities consist of the following (in millions):

	As of December 31,
	2016		2015
Other current assets:
Prepaid expenses	$	48	$	43
Margin deposits	8		33
Assets from price risk management activities	18		10
Other	3		2
	$	77	$	88
Accrued expenses and other current liabilities:
Regulatory liabilities—current	$	51	$	55
Accrued employee compensation and benefits	52		51
Accrued interest payable	25		25
Accrued dividends payable	30		28
Accrued taxes payable	25		25
Other	71		75
	$	254	$	259