Balance Sheet Components (Tables)

9 Months Ended

Sep. 30, 2015

Balance Sheet Components [Abstract]

Schedule of Other Current Assets [Table Text Block]

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

	September 30, 2015		December 31, 2014
Prepaid expenses	$	24	$	39
Current deferred income tax asset	39		33
Margin deposits	20		11
Accrued sales tax refund related to Tucannon River Wind Farm	—		23
Assets from price risk management activities	7		6
Other	2		3
Other current assets	$	92	$	115

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

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

	September 30, 2015			December 31, 2014
Electric utility plant	$	8,458		$	8,161
Construction work-in-progress	508			417
Total cost	8,966			8,578
Less: accumulated depreciation and amortization	(3,046		)	(2,899		)
Electric utility plant, net	$	5,920		$	5,679

Schedule of Regulatory Assets and Liabilities [Text Block]

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

	September 30, 2015					December 31, 2014
	Current			Noncurrent		Current			Noncurrent
Regulatory assets:
Price risk management	$	108		$	184	$	100		$	121
Pension and other postretirement plans	—			232		—			247
Deferred income taxes	—			87		—			86
Debt issuance costs	—			17		—			15
Deferred capital projects	5			—		19			—
Other	9			27		14			25
Total regulatory assets	$	122		$	547	$	133		$	494
Regulatory liabilities:
Asset retirement removal costs	$	—		$	833	$	—		$	804
Trojan decommissioning activities	19			21		23			34
Asset retirement obligations	—			44		—			39
Other	26			41		37			29
Total regulatory liabilities	$	45	*	$	939	$	60	*	$	906

* 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):

	September 30, 2015		December 31, 2014
Regulatory liabilities—current	$	45	$	60
Accrued employee compensation and benefits	44		51
Accrued interest payable	40		26
Accrued dividends payable	28		23
Accrued taxes payable	40		22
Other	57		54
Total accrued expenses and other current liabilities	$	254	$	236

Schedule of Asset Retirement Obligations [Table Text Block]

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

	September 30, 2015		December 31, 2014
Trojan decommissioning activities	$	43	$	41
Utility plant	83		64
Non-utility property	11		11
Asset retirement obligations	$	137	$	116

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 September 30,						Nine Months Ended September 30,
	2015			2014			2015			2014
Service cost	$	4		$	4		$	13		$	11
Interest cost	8			8			24			25
Expected return on plan assets	(10		)	(9		)	(30		)	(29		)
Amortization of net actuarial loss	5			4			15			13
Net periodic benefit cost	$	7		$	7		$	22		$	20