Balance Sheet Components (Tables)

6 Months Ended

Jun. 30, 2017

Balance Sheet Components [Abstract]

Schedule of Other Current Assets [Table Text Block]

Other current assets consist of the following (in millions):

	June 30, 2017		December 31, 2016
Prepaid expenses	$	34	$	48
Margin deposits	1		8
Assets from price risk management activities	5		18
Other	3		3
Other current assets	$	43	$	77

Schedule of Public Utility Property, Plant, and Equipment [Table Text Block]

Electric utility plant, net consists of the following (in millions):

	June 30, 2017			December 31, 2016
Electric utility plant	$	9,674		$	9,534
Construction work-in-progress	346			213
Total cost	10,020			9,747
Less: accumulated depreciation and amortization	(3,447		)	(3,313		)
Electric utility plant, net	$	6,573		$	6,434

Schedule of Regulatory Assets and Liabilities [Text Block]

Regulatory assets and liabilities consist of the following (in millions):

	June 30, 2017					December 31, 2016
	Current			Noncurrent		Current			Noncurrent
Regulatory assets:
Price risk management	$	41		$	156	$	26		$	120
Pension and other postretirement plans	—			229		—			235
Deferred income taxes	—			82		—			86
Debt issuance costs	—			20		—			22
Other	6			49		10			35
Total regulatory assets	$	47		$	536	$	36		$	498
Regulatory liabilities:
Asset retirement removal costs	$	—		$	910	$	—		$	887
Trojan decommissioning activities	8			—		18			—
Asset retirement obligations	—			51		—			49
Other	26			28		33			22
Total regulatory liabilities	$	34	*	$	989	$	51	*	$	958

* Included in Accrued expenses and other current liabilities in the condensed consolidated balance sheets.

Other Liabilities Disclosure [Text Block]

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

	June 30, 2017		December 31, 2016
Regulatory liabilities—current	$	34	$	51
Accrued employee compensation and benefits	52		52
Accrued interest payable	25		25
Accrued dividends payable	31		30
Accrued taxes payable	25		25
Other	59		71
Total accrued expenses and other current liabilities	$	226	$	254

Pension and Other Postretirement Benefits Disclosure [Text Block]

Components of net periodic benefit cost under the defined benefit pension plan are as follows (in millions):

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Service cost	$	4		$	4		$	8		$	8
Interest cost	9			8			17			16
Expected return on plan assets	(10		)	(10		)	(20		)	(20		)
Amortization of net actuarial loss	3			4			6			8
Net periodic benefit cost	$	6		$	6		$	11		$	12