Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2018

Balance Sheet Components [Abstract]

Schedule of Other Current Assets [Table Text Block]

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

	March 31, 2018		December 31, 2017
Prepaid expenses	$	56	$	50
Assets from price risk management activities	4		6
Margin deposits	17		11
Other	4		6
Other current assets	$	81	$	73

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

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

	March 31, 2018			December 31, 2017
Electric utility plant	$	9,984		$	9,914
Construction work-in-progress	430			391
Total cost	10,414			10,305
Less: accumulated depreciation and amortization	(3,633		)	(3,564		)
Electric utility plant, net	$	6,781		$	6,741

Schedule of Regulatory Assets and Liabilities [Text Block]

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

	March 31, 2018					December 31, 2017
	Current			Noncurrent		Current			Noncurrent
Regulatory assets:
Price risk management	$	62		$	144	$	53		$	151
Pension and other postretirement plans	—			214		—			218
Debt issuance costs	—			18		—			19
Trojan decommissioning activities	—			25		—			—
Other	10			47		9			50
Total regulatory assets	$	72		$	448	$	62		$	438
Regulatory liabilities:
Asset retirement removal costs	$	—		$	944	$	—		$	933
Deferred income taxes	—			281		—			277
Trojan decommissioning activities	2			—		3			—
Asset retirement obligations	—			53		—			52
Other	26			45		28			26
Total regulatory liabilities	$	28	*	$	1,323	$	31	*	$	1,288

* 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):

	March 31, 2018		December 31, 2017
Accrued employee compensation and benefits	$	39	$	60
Accrued taxes payable	32		31
Accrued interest payable	43		27
Accrued dividends payable	31		31
Regulatory liabilities—current	28		31
Other	56		61
Total accrued expenses and other current liabilities	$	229	$	241

Schedule of Asset Retirement Obligations [Table Text Block]

Asset retirement obligations (AROs) consist of the following (in millions):

	March 31, 2018		December 31, 2017
Trojan decommissioning activities	$	68	$	45
Utility plant	110		109
Non-utility property	13		13
Asset retirement obligations	$	191	$	167

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 March 31,
	2018			2017
Service cost	$	5		$	4
Interest cost	8			8
Expected return on plan assets	(10		)	(10		)
Amortization of net actuarial loss	4			3
Net periodic benefit cost	$	7		$	5