Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

Net periodic benefit cost for the UK Plan included the following components for the years ended December 31 (in millions):

	2017			2016			2015
Service cost	$	23		$	20		$	24
Interest cost	58			72			79
Expected return on plan assets	(100		)	(110		)	(116		)
Settlement	31			—			—
Net amortization	63			44			62
Net periodic benefit cost	$	75		$	26		$	49

Net periodic benefit cost for the plans included the following components for the years ended December 31 (in millions):

	Pension									Other Postretirement
	2017			2016			2015			2017			2016			2015
Service cost	$	24		$	29		$	33		$	9		$	9		$	11
Interest cost	116			126			121			29			31			31
Expected return on plan assets	(160		)	(160		)	(169		)	(40		)	(41		)	(45		)
Net amortization	25			46			53			(14		)	(12		)	(11		)
Net periodic benefit cost (credit)	$	5		$	41		$	38		$	(16	)	$	(13	)	$	(14	)

Changes in Fair Value of Plan Assets [Table Text Block]

The following table is a reconciliation of the fair value of plan assets for the years ended December 31 (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Plan assets at fair value, beginning of year	$	2,525		$	2,489		$	666		$	662
Employer contributions	64			78			5			2
Participant contributions	—			—			10			10
Actual return on plan assets	390			163			106			41
Settlement	(15		)	(11		)	—			—
Benefits paid	(203		)	(194		)	(51		)	(49		)
Plan assets at fair value, end of year	$	2,761		$	2,525		$	736		$	666

The following table is a reconciliation of the fair value of plan assets for the years ended December 31 (in millions):

	2017			2016
Plan assets at fair value, beginning of year	$	2,169		$	2,276
Employer contributions	58			55
Participant contributions	1			1
Actual return on plan assets	145			349
Settlement	(144		)	—
Benefits paid	(68		)	(115		)
Foreign currency exchange rate changes	207			(397		)
Plan assets at fair value, end of year	$	2,368		$	2,169

Changes in Projected Benefit Obligations [Table Text Block]

The following table is a reconciliation of the benefit obligations for the years ended December 31 (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Benefit obligation, beginning of year	$	2,952		$	2,934		$	734		$	740
Service cost	24			29			9			9
Interest cost	116			126			29			31
Participant contributions	—			—			10			10
Actuarial loss (gain)	132			67			(10		)	(7		)
Amendment	—			1			—			—
Settlement	(15		)	(11		)	—			—
Benefits paid	(203		)	(194		)	(51		)	(49		)
Benefit obligation, end of year	$	3,006		$	2,952		$	721		$	734
Accumulated benefit obligation, end of year	$	2,988		$	2,929

following table is a reconciliation of the benefit obligation for the years ended December 31 (in millions):

	2017			2016
Benefit obligation, beginning of year	$	2,125		$	2,142
Service cost	23			20
Interest cost	58			72
Participant contributions	1			1
Actuarial loss (gain)	(4		)	387
Settlement	(131		)	—
Benefits paid	(68		)	(115		)
Foreign currency exchange rate changes	197			(382		)
Benefit obligation, end of year	$	2,201		$	2,125
Accumulated benefit obligation, end of year	$	1,933		$	1,858

Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]

The funded status of the plans and the amounts recognized on the Consolidated Balance Sheets as of December 31 are as follows (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Plan assets at fair value, end of year	$	2,761		$	2,525		$	736		$	666
Benefit obligation, end of year	3,006			2,952			721			734
Funded status	$	(245	)	$	(427	)	$	15		$	(68	)
Amounts recognized on the Consolidated Balance Sheets:
Other assets	$	66		$	26		$	32		$	19
Other current liabilities	(14		)	(15		)	—			—
Other long-term liabilities	(297		)	(438		)	(17		)	(87		)
Amounts recognized	$	(245	)	$	(427	)	$	15		$	(68	)

The fair value of plan assets, projected benefit obligation and accumulated benefit obligation for (1) pension and other postretirement benefit plans with a projected benefit obligation in excess of the fair value of plan assets and (2) pension plans with an accumulated benefit obligation in excess of the fair value of plan assets as of December 31 are as follows (in millions):

	Pension				Other Postretirement
	2017		2016		2017		2016
Fair value of plan assets	$	2,016	$	1,841	$	126	$	413
Projected benefit obligation	$	2,327	$	2,294	$	143	$	500
Accumulated benefit obligation	$	2,316	$	2,278

The funded status of the UK Plan and the amounts recognized on the Consolidated Balance Sheets as of December 31 are as follows (in millions):

	2017		2016
Plan assets at fair value, end of year	$	2,368	$	2,169
Benefit obligation, end of year	2,201		2,125
Funded status	$	167	$	44
Amounts recognized on the Consolidated Balance Sheets:
Other assets	$	167	$	44

Net Periodic Benefit Costs Not Yet Recognized [Table Text Block]

A reconciliation of the amounts not yet recognized as components of net periodic benefit cost, which are included in accumulated other comprehensive loss on the Consolidated Balance Sheets, for the years ended December 31 is as follows (in millions):

	2017			2016
Balance, beginning of year	$	590		$	592
Net (gain) loss arising during the year	(50		)	148
Settlement	(17		)	—
Net amortization	(63		)	(44		)
Foreign currency exchange rate changes	50			(106		)
Total	(80		)	(2		)
Balance, end of year	$	510		$	590

The portion of the funded status of the plans not yet recognized in net periodic benefit cost as of December 31 is as follows (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Net loss	$	649		$	775		$	14		$	88
Prior service credit	(3		)	(7		)	(37		)	(52		)
Regulatory deferrals	(4		)	(7		)	7			7
Total	$	642		$	761		$	(16	)	$	43

A reconciliation of the amounts not yet recognized as components of net periodic benefit cost for the years ended December 31, 2017 and 2016 is as follows (in millions):

							Accumulated
							Other
	Regulatory			Regulatory			Comprehensive
	Asset			Liability			Loss		Total
Pension
Balance, December 31, 2015	$	729		$	(1	)	$	13	$	741
Net loss (gain) arising during the year	76			(11		)	—		65
Net prior service cost arising during the year	1			—			—		1
Net amortization	(45		)	(1		)	—		(46		)
Total	32			(12		)	—		20
Balance, December 31, 2016	761			(13		)	13		761
Net (gain) loss arising during the year	(68		)	(29		)	3		(94		)
Net amortization	(28		)	(1		)	4		(25		)
Total	(96		)	(30		)	7		(119		)
Balance, December 31, 2017	$	665		$	(43	)	$	20	$	642

	Regulatory			Regulatory
	Asset			Liability			Total
Other Postretirement
Balance, December 31, 2015	$	49		$	(12	)	$	37
Net gain arising during the year	(5		)	(1		)	(6		)
Net amortization	11			1			12
Total	6			—			6
Balance, December 31, 2016	55			(12		)	43
Net gain arising during the year	(52		)	(21		)	(73		)
Net amortization	7			7			14
Total	(45		)	(14		)	(59		)
Balance, December 31, 2017	$	10		$	(26	)	$	(16	)

The portion of the funded status of the UK Plan not yet recognized in net periodic benefit cost as of December 31 is as follows (in millions):

	2017		2016
Net loss	$	510	$	590

Defined Benefit Plans, Amounts To Be Recognized In Following Year [Table Text Block]

The net loss, prior service credit and regulatory deferrals that will be amortized in 2018 into net periodic benefit cost are estimated to be as follows (in millions):

	Net		Prior Service			Regulatory
	Loss		Credit			Deferrals			Total
Pension	$	32	$	(1	)	$	(3	)	$	28
Other postretirement	1		(15		)	1			(13		)
Total	$	33	$	(16	)	$	(2	)	$	15

Plan Assumptions [Table Text Block]

Weighted-average assumptions used to determine benefit obligations and net periodic benefit cost were as follows:

	Pension						Other Postretirement
	2017		2016		2015		2017		2016		2015
Benefit obligations as of December 31:
Discount rate	3.60	%	4.06	%	4.43	%	3.57	%	4.01	%	4.33	%
Rate of compensation increase	2.75	%	2.75	%	2.75	%	NA		NA		NA
Net periodic benefit cost for the years ended December 31:
Discount rate	4.06	%	4.43	%	4.00	%	4.01	%	4.33	%	3.93	%
Expected return on plan assets	6.55	%	6.78	%	6.88	%	6.73	%	7.03	%	7.00	%
Rate of compensation increase	2.75	%	2.75	%	2.75	%	NA		NA		NA

Assumptions used to determine benefit obligations and net periodic benefit cost were as follows:

	2017		2016		2015
Benefit obligations as of December 31:
Discount rate	2.60	%	2.70	%	3.70	%
Rate of compensation increase	3.45	%	3.00	%	2.90	%
Rate of future price inflation	2.95	%	3.00	%	2.90	%
Net periodic benefit cost for the years ended December 31:
Discount rate	2.70	%	3.70	%	3.60	%
Expected return on plan assets	5.00	%	5.60	%	5.60	%
Rate of compensation increase	3.00	%	2.90	%	2.80	%
Rate of future price inflation	3.00	%	2.90	%	2.80	%

In establishing its assumption as to the expected return on plan assets, the Company utilizes the asset allocation and return assumptions for each asset class based on historical performance and forward-looking views of the financial markets.

	2017		2016
Assumed healthcare cost trend rates as of December 31:
Healthcare cost trend rate assumed for next year	7.10	%	7.40	%
Rate that the cost trend rate gradually declines to	5.00	%	5.00	%
Year that the rate reaches the rate it is assumed to remain at	2025		2025

Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]

A one percentage-point change in assumed healthcare cost trend rates would have the following effects (in millions):

	One Percentage-Point
	Increase		Decrease
Increase (decrease) in:
Total service and interest cost for the year ended December 31, 2017	$	—	$	—
Other postretirement benefit obligation as of December 31, 2017	4		(4		)

Expected Benefit Payments [Table Text Block]

Employer contributions to the UK Plan are expected to be £45 million during 2018. The expected benefit payments to participants in the UK Plan for 2018 through 2022 and for the five years thereafter excluding lump sum settlement elections, using the foreign currency exchange rate as of December 31, 2017, are summarized below (in millions):

2018	$	72
2019	74
2020	75
2021	77
2022	79
2023-2027	427

The expected benefit payments to participants in the Company's pension and other postretirement benefit plans for 2018 through 2022 and for the five years thereafter are summarized below (in millions):

	Projected Benefit
	Payments
			Other
	Pension		Postretirement
2018	$	226	$	54
2019	224		55
2020	224		57
2021	222		55
2022	214		54
2023-2027	979		243

Allocation of Plan Assets [Table Text Block]

The target allocations (percentage of plan assets) for the UK Plan assets are as follows as of December 31, 2017:

	%
Debt securities(1)	50-55
Equity securities(1)	35-40
Real estate funds and other	5-15

(1) For purposes of target allocation percentages and consistent with the plans' investment policy, investment funds have been allocated based on the underlying investments in debt and equity securities.

The target allocations (percentage of plan assets) for the Company's pension and other postretirement benefit plan assets are as follows as of December 31, 2017:

		Other
	Pension	Postretirement
	%	%
PacifiCorp:
Debt securities(1)	33-38	33-37
Equity securities(1)	49-60	61-65
Limited partnership interests	7-12	1-3
Other	0-1	0-1
MidAmerican Energy:
Debt securities(1)	20-50	25-45
Equity securities(1)	60-80	45-80
Real estate funds	2-8	—
Other	0-3	0-5
NV Energy:
Debt securities(1)	53-77	40
Equity securities(1)	23-47	60

(1) For purposes of target allocation percentages and consistent with the plans' investment policy, investment funds are allocated based on the underlying investments in debt and equity securities.

Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following table presents the fair value of plan assets, by major category, for the Company's defined benefit pension plans (in millions):

	Input Levels for Fair Value Measurements(1)
	Level 1		Level 2		Level 3		Total
As of December 31, 2017:
Cash equivalents	$	10	$	76	$	—	$	86
Debt securities:
United States government obligations	218		—		—		218
Corporate obligations	—		350		—		350
Municipal obligations	—		16		—		16
Agency, asset and mortgage-backed obligations	—		110		—		110
Equity securities:
United States companies	622		—		—		622
International companies	136		—		—		136
Investment funds(2)	83		20		—		103
Total assets in the fair value hierarchy	$	1,069	$	572	$	—	1,641
Investment funds(2) measured at net asset value							1,019
Limited partnership interests(3) measured at net asset value							63
Real estate funds measured at net asset value							38
Total assets measured at fair value							$	2,761
As of December 31, 2016:
Cash equivalents	$	4	$	54	$	—	$	58
Debt securities:
United States government obligations	161		—		—		161
International government obligations	—		2		—		2
Corporate obligations	—		295		—		295
Municipal obligations	—		20		—		20
Agency, asset and mortgage-backed obligations	—		112		—		112
Equity securities:
United States companies	583		—		—		583
International companies	117		—		—		117
Investment funds(2)	146		—		—		146
Total assets in the fair value hierarchy	$	1,011	$	483	$	—	1,494
Investment funds(2) measured at net asset value							920
Limited partnership interests(3) measured at net asset value							61
Real estate funds measured at net asset value							50
Total assets measured at fair value							$	2,525

(1) Refer to Note 15 for additional discussion regarding the three levels of the fair value hierarchy.

(2) Investment funds are comprised of mutual funds and collective trust funds. These funds consist of equity and debt securities of approximately 62% and 38%, respectively, for both 2017 and 2016. Additionally, these funds are invested in United States and international securities of approximately 68% and 32%, respectively, for 2017 and 60% and 40%, respectively, for 2016.

(3) Limited partnership interests include several funds that invest primarily in real estate, buyout, growth equity and venture capital.

The following table presents the fair value of plan assets, by major category, for the Company's defined benefit other postretirement plans (in millions):

	Input Levels for Fair Value Measurements(1)
	Level 1		Level 2		Level 3		Total
As of December 31, 2017:
Cash equivalents	$	11	$	3	$	—	$	14
Debt securities:
United States government obligations	20		—		—		20
Corporate obligations	—		36		—		36
Municipal obligations	—		46		—		46
Agency, asset and mortgage-backed obligations	—		29		—		29
Equity securities:
United States companies	185		—		—		185
International companies	8		—		—		8
Investment funds	219		1		—		220
Total assets in the fair value hierarchy	$	443	$	115	$	—	558
Investment funds measured at net asset value							174
Limited partnership interests measured at net asset value							4
Total assets measured at fair value							$	736
As of December 31, 2016:
Cash equivalents	$	18	$	2	$	—	$	20
Debt securities:
United States government obligations	19		—		—		19
Corporate obligations	—		29		—		29
Municipal obligations	—		39		—		39
Agency, asset and mortgage-backed obligations	—		25		—		25
Equity securities:
United States companies	217		—		—		217
International companies	5		—		—		5
Investment funds(2)	152		—		—		152
Total assets in the fair value hierarchy	$	411	$	95	$	—	506
Investment funds(2) measured at net asset value							156
Limited partnership interests(3) measured at net asset value							4
Total assets measured at fair value							$	666

(1) Refer to Note 15 for additional discussion regarding the three levels of the fair value hierarchy.

(2) Investment funds are comprised of mutual funds and collective trust funds. These funds consist of equity and debt securities of approximately 68% and 32%, respectively, for 2017 and 63% and 37%, respectively, for 2016. Additionally, these funds are invested in United States and international securities of approximately 73% and 27%, respectively, for 2017 and 72% and 28%, respectively, for 2016.

(3) Limited partnership interests include several funds that invest primarily in real estate, buyout, growth equity and venture capital.

The following table presents the fair value of the UK Plan assets, by major category (in millions):

	Input Levels for Fair Value Measurements(1)
	Level 1		Level 2		Level 3		Total
As of December 31, 2017:
Cash equivalents	$	4	$	30	$	—	$	34
Debt securities:
United Kingdom government obligations	870		—		—		870
Equity securities:
Investment funds(2)	—		1,027		—		1,027
Real estate funds	—		—		230		230
Total	$	874	$	1,057	$	230	2,161
Investment funds(2) measured at net asset value							207
Total assets measured at fair value							$	2,368
As of December 31, 2016:
Cash equivalents	$	4	$	83	$	—	$	87
Debt securities:
United Kingdom government obligations	718		—		—		718
Equity securities:
Investment funds(2)	—		1,095		—		1,095
Real estate funds	—		—		105		105
Total	$	722	$	1,178	$	105	2,005
Investment funds(2) measured at net asset value							164
Total assets measured at fair value							$	2,169

(1) Refer to Note 15 for additional discussion regarding the three levels of the fair value hierarchy.

(2) Investment funds are comprised of mutual funds and collective trust funds. These funds consist of equity and debt securities of approximately 21% and 79%, respectively, for 2017 and 44% and 56%, respectively, for 2016.

The following table presents the Company's assets and liabilities recognized on the Consolidated Balance Sheets and measured at fair value on a recurring basis (in millions):

	Input Levels for Fair Value Measurements
	Level 1			Level 2			Level 3			Other(1)			Total
As of December 31, 2017:
Assets:
Commodity derivatives	$	1		$	42		$	104		$	(29	)	$	118
Interest rate derivatives	—			15			9			—			24
Mortgage loans held for sale	—			465			—			—			465
Money market mutual funds(2)	685			—			—			—			685
Debt securities:
United States government obligations	176			—			—			—			176
International government obligations	—			5			—			—			5
Corporate obligations	—			36			—			—			36
Municipal obligations	—			2			—			—			2
Equity securities:
United States companies	288			—			—			—			288
International companies	1,968			—			—			—			1,968
Investment funds	178			—			—			—			178
	$	3,296		$	565		$	113		$	(29	)	$	3,945
Liabilities:
Commodity derivatives	$	(3	)	$	(167	)	$	(10	)	$	105		$	(75	)
Interest rate derivatives	—			(8		)	—			—			(8		)
	$	(3	)	$	(175	)	$	(10	)	$	105		$	(83	)

As of December 31, 2016:
Assets:
Commodity derivatives	$	5		$	49		$	87		$	(22	)	$	119
Interest rate derivatives	—			16			7			—			23
Mortgage loans held for sale	—			359			—			—			359
Money market mutual funds(2)	586			—			—			—			586
Debt securities:
United States government obligations	161			—			—			—			161
International government obligations	—			3			—			—			3
Corporate obligations	—			36			—			—			36
Municipal obligations	—			2			—			—			2
Agency, asset and mortgage-backed obligations	—			2			—			—			2
Equity securities:
United States companies	250			—			—			—			250
International companies	1,190			—			—			—			1,190
Investment funds	147			—			—			—			147
	$	2,339		$	467		$	94		$	(22	)	$	2,878
Liabilities:
Commodity derivatives	$	(2	)	$	(199	)	$	(27	)	$	96		$	(132	)
Interest rate derivatives	(1		)	(11		)	(1		)	—			(13		)
	$	(3	)	$	(210	)	$	(28	)	$	96		$	(145	)

(1) Represents netting under master netting arrangements and a net cash collateral receivable of $76 million and $74 million as of December 31, 2017 and 2016, respectively.

(2) Amounts are included in cash and cash equivalents; other current assets; and noncurrent investments and restricted cash and investments on the Consolidated Balance Sheets. The fair value of these money market mutual funds approximates cost.

Level Three Defined Benefit Plan Assets Roll Forward [Table Text Block]

The following table reconciles the beginning and ending balances of the UK Plan assets measured at fair valueusing significant Level 3 inputs for the years ended December 31 (in millions):

	Real Estate Funds
	2017		2016			2015
Beginning balance	$	105	$	204		$	199
Actual return on plan assets still held at period end	6		10			18
Purchases (sales)	104		(80		)	—
Foreign currency exchange rate changes	15		(29		)	(13		)
Ending balance	$	230	$	105		$	204

PacifiCorp [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

Net periodic benefit cost for the plans included the following components for the years ended December 31 (in millions):

	Pension									Other Postretirement
	2017			2016			2015			2017			2016			2015
Service cost	$	—		$	4		$	4		$	2		$	2		$	3
Interest cost	49			54			53			14			15			16
Expected return on plan assets	(72		)	(75		)	(77		)	(21		)	(21		)	(23		)
Net amortization	14			34			42			(6		)	(5		)	(4		)
Net periodic benefit cost (credit)	$	(9	)	$	17		$	22		$	(11	)	$	(9	)	$	(8	)

Changes in Fair Value of Plan Assets [Table Text Block]

The following table is a reconciliation of the fair value of plan assets for the years ended December 31 (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Plan assets at fair value, beginning of year	$	999		$	1,043		$	302		$	305
Employer contributions	54			5			1			1
Participant contributions	—			—			7			6
Actual return on plan assets	166			51			49			17
Benefits paid	(108		)	(100		)	(27		)	(27		)
Plan assets at fair value, end of year	$	1,111		$	999		$	332		$	302

Changes in Projected Benefit Obligations [Table Text Block]

The following table is a reconciliation of the benefit obligations for the years ended December 31 (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Benefit obligation, beginning of year	$	1,276		$	1,289		$	358		$	362
Service cost	—			4			2			2
Interest cost	49			54			14			15
Participant contributions	—			—			7			6
Actuarial (gain) loss	34			29			(23		)	—
Benefits paid	(108		)	(100		)	(27		)	(27		)
Benefit obligation, end of year	$	1,251		$	1,276		$	331		$	358
Accumulated benefit obligation, end of year	$	1,251		$	1,276

Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]

The funded status of the plans and the amounts recognized on the Consolidated Balance Sheets as of December 31 are as follows (in millions):

	Pension						Other Postretirement
	2017			2016			2017		2016
Plan assets at fair value, end of year	$	1,111		$	999		$	332	$	302
Less - Benefit obligation, end of year	1,251			1,276			331		358
Funded status	$	(140	)	$	(277	)	$	1	$	(56	)
Amounts recognized on the Consolidated Balance Sheets:
Other assets	$	5		$	—		$	1	$	—
Other current liabilities	(4		)	(5		)	—		—
Other long-term liabilities	(141		)	(272		)	—		(56		)
Amounts recognized	$	(140	)	$	(277	)	$	1	$	(56	)

Net Periodic Benefit Costs Not Yet Recognized [Table Text Block]

The portion of the funded status of the plans not yet recognized in net periodic benefit cost as of December 31 is as follows (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Net loss (gain)	$	442		$	518		$	(12	)	$	39
Prior service credit	—			—			(6		)	(13		)
Regulatory deferrals	(4		)	(7		)	7			8
Total	$	438		$	511		$	(11	)	$	34

A reconciliation of the amounts not yet recognized as components of net periodic benefit cost for the years ended December 31, 2017 and 2016 is as follows (in millions):

				Accumulated
				Other
	Regulatory			Comprehensive
	Asset			Loss			Total
Pension
Balance, December 31, 2015	$	473		$	19		$	492
Net loss arising during the year	51			2			53
Net amortization	(33		)	(1		)	(34		)
Total	18			1			19
Balance, December 31, 2016	491			20			511
Net (gain) loss arising during the year	(60		)	1			(59		)
Net amortization	(13		)	(1		)	(14		)
Total	(73		)	—			(73		)
Balance, December 31, 2017	$	418		$	20		$	438

	Regulatory
	Asset (Liability)
Other Postretirement
Balance, December 31, 2015	$	26
Net loss arising during the year	3
Net amortization	5
Total	8
Balance, December 31, 2016	34
Net gain arising during the year	(51		)
Net amortization	6
Total	(45		)
Balance, December 31, 2017	$	(11	)

Defined Benefit Plans, Amounts To Be Recognized In Following Year [Table Text Block]

The net loss, prior service credit and regulatory deferrals that will be amortized in 2018 into net periodic benefit cost are estimated to be as follows (in millions):

	Net		Prior Service			Regulatory
	Loss		Credit			Deferrals			Total
Pension	$	16	$	—		$	(2	)	$	14
Other postretirement	—		(6		)	1			(5		)
Total	$	16	$	(6	)	$	(1	)	$	9

Plan Assumptions [Table Text Block]

Assumptions used to determine benefit obligations and net periodic benefit cost were as follows:

	Pension						Other Postretirement
	2017		2016		2015		2017		2016		2015
Benefit obligations as of December 31:
Discount rate	3.60	%	4.05	%	4.40	%	3.60	%	4.05	%	4.35	%
Rate of compensation increase	N/A		N/A		2.75		N/A		N/A		N/A
Net periodic benefit cost for the years ended December 31:
Discount rate	4.05	%	4.40	%	4.00	%	4.05	%	4.35	%	3.99	%
Expected return on plan assets	7.25		7.50		7.50		7.25		7.50		7.08
Rate of compensation increase	N/A		2.75		2.75		N/A		N/A		N/A

In establishing its assumption as to the expected return on plan assets, PacifiCorp utilizes the asset allocation and return assumptions for each asset class based on historical performance and forward-looking views of the financial markets.

As a result of a plan amendment effective on January 1, 2017, the benefit obligation for the Retirement Plan is no longer affected by future increases in compensation. As a result of a labor settlement reached with UMWA in December 2014, the benefit obligation for the other postretirement plan is no longer affected by healthcare cost trends.

Expected Benefit Payments [Table Text Block]

The expected benefit payments to participants in PacifiCorp's pension and other postretirement benefit plans for 2018 through 2022 and for the five years thereafter are summarized below (in millions):

	Projected Benefit Payments
	Pension		Other Postretirement
2018	$	108	$	25
2019	107		25
2020	103		26
2021	99		23
2022	94		23
2023-2027	393		100

Allocation of Plan Assets [Table Text Block]

The target allocations (percentage of plan assets) for PacifiCorp's pension and other postretirement benefit plan assets are as follows as of December 31, 2017:

	Pension(1)	Other Postretirement(1)
	%	%
Debt securities(2)	33 - 38	33 - 37
Equity securities(2)	49 - 60	61 - 65
Limited partnership interests	7 - 12	1 - 3
Other	0 - 1	0 - 1

(1) PacifiCorp's Retirement Plan trust includes a separate account that is used to fund benefits for the other postretirement benefit plan. In addition to this separate account, the assets for the other postretirement benefit plan are held in Voluntary Employees' Beneficiary Association ("VEBA") trusts, each of which has its own investment allocation strategies. Target allocations for the other postretirement benefit plan include the separate account of the Retirement Plan trust and the VEBA trusts.

(2) For purposes of target allocation percentages and consistent with the plans' investment policy, investment funds are allocated based on the underlying investments in debt and equity securities.

Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following table presents the fair value of plan assets, by major category, for PacifiCorp's defined benefit pension plan (in millions):

	Input Levels for Fair Value Measurements
	Level 1(1)		Level 2(1)		Level 3(1)		Total
As of December 31, 2017:
Cash equivalents	$	—	$	43	$	—	$	43
Debt securities:
United States government obligations	45		—		—		45
Corporate obligations	—		60		—		60
Municipal obligations	—		9		—		9
Agency, asset and mortgage-backed obligations	—		37		—		37
Equity securities:
United States companies	416		—		—		416
International companies	22		—		—		22
Total assets in the fair value hierarchy	$	483	$	149	$	—	632
Investment funds(2) measured at net asset value							416
Limited partnership interests(3) measured at net asset value							63
Investments at fair value							$	1,111
As of December 31, 2016:
Cash equivalents	$	—	$	10	$	—	$	10
Debt securities:
United States government obligations	25		—		—		25
Corporate obligations	—		36		—		36
Municipal obligations	—		6		—		6
Agency, asset and mortgage-backed obligations	—		37		—		37
Equity securities:
United States companies	389		—		—		389
International companies	15		—		—		15
Investment funds(2)	83		—		—		83
Total assets in the fair value hierarchy	$	512	$	89	$	—	601
Investment funds(2) measured at net asset value							337
Limited partnership interests(3) measured at net asset value							61
Investments at fair value							$	999

(1) Refer to Note 12 for additional discussion regarding the three levels of the fair value hierarchy.

(2) Investment funds are substantially comprised of mutual funds and collective trust funds. These funds consist of equity and debt securities of approximately60% and 40% respectively, for 2017 and 54% and 46%, respectively, for 2016, and are invested in United States and international securities of approximately 57% and 43%, respectively, for 2017 and 39% and 61%, respectively, for 2016.

(3) Limited partnership interests include several funds that invest primarily in real estate, buyout, growth equity and venture capital.

The following table presents the fair value of plan assets, by major category, for PacifiCorp's defined benefit other postretirement plan (in millions):

	Input Levels for Fair Value Measurements
	Level 1(1)		Level 2(1)		Level 3(1)		Total
As of December 31, 2017:
Cash and cash equivalents	$	4	$	3	$	—	$	7
Debt securities:
United States government obligations	11		—		—		11
Corporate obligations	—		16		—		16
Municipal obligations	—		2		—		2
Agency, asset and mortgage-backed obligations	—		16		—		16
Equity securities:
United States companies	98		—		—		98
International companies	6		—		—		6
Investment funds(2)	32		—		—		32
Total assets in the fair value hierarchy	$	151	$	37	$	—	188
Investment funds(2) measured at net asset value							140
Limited partnership interests(3) measured at net asset value							4
Investments at fair value							$	332
As of December 31, 2016:
Cash and cash equivalents	$	4	$	1	$	—	$	5
Debt securities:
United States government obligations	11		—		—		11
Corporate obligations	—		13		—		13
Municipal obligations	—		2		—		2
Agency, asset and mortgage-backed obligations	—		13		—		13
Equity securities:
United States companies	93		—		—		93
International companies	4		—		—		4
Investment funds(2)	32		—		—		32
Total assets in the fair value hierarchy	$	144	$	29	$	—	173
Investment funds(2) measured at net asset value							125
Limited partnership interests(3) measured at net asset value							4
Investments at fair value							$	302

(1) Refer to Note 12 for additional discussion regarding the three levels of the fair value hierarchy.

(2) Investment funds are substantially comprised of mutual funds and collective trust funds. These funds consist of equity and debt securities of approximately63% and 37%, respectively, for 2017 and 62% and 38%, respectively, for 2016, and are invested in United States and international securities of approximately 77% and 23%, respectively, for 2017 and 71% and 29%, respectively, for 2016.

(3) Limited partnership interests include several funds that invest primarily in real estate, buyout, growth equity and venture capital.

The following table presents PacifiCorp's assets and liabilities recognized on the Consolidated Balance Sheets and measured at fair value on a recurring basis (in millions):

	Input Levels for Fair Value Measurements
	Level 1		Level 2			Level 3		Other(1)			Total
As of December 31, 2017:
Assets:
Commodity derivatives	$	—	$	13		$	—	$	(4	)	$	9
Money market mutual funds(2)	21		—			—		—			21
Investment funds	21		—			—		—			21
	$	42	$	13		$	—	$	(4	)	$	51
Liabilities - Commodity derivatives	$	—	$	(117	)	$	—	$	78		$	(39	)
As of December 31, 2016:
Assets:
Commodity derivatives	$	—	$	27		$	—	$	(7	)	$	20
Money market mutual funds (2)	13		—			—		—			13
Investment funds	17		—			—		—			17
	$	30	$	27		$	—	$	(7	)	$	50
Liabilities - Commodity derivatives	$	—	$	(104	)	$	—	$	76		$	(28	)

(1) Represents netting under master netting arrangements and a net cash collateral receivable of $74 million and $69 million as of December 31, 2017 and 2016, respectively.

(2) Amounts are included in cash and cash equivalents, other current assets and other assets on the Consolidated Balance Sheets. The fair value of these money market mutual funds approximates cost.

Schedule of Multiemployer Plans [Table Text Block]

The following table presents PacifiCorp's and Energy West Mining Company's participation in individually significant joint trustee and multiemployer pension plans for the years ended December 31 (dollars in millions):

		PPA zone status or
		plan funded status percentage for
		plan years beginning July 1,					Contributions(1)
Plan name	Employer Identification Number	2017	2016	2015	Funding improvement plan	Surcharge imposed under PPA(1)	2017		2016		2015		Year contributions to plan exceeded more than 5% of total contributions(2)
UMWA 1974 Pension Plan	52-1050282	Critical and Declining	Critical and Declining	Critical and Declining	Implemented	Yes	$	—	$	—	$	1	None
Local 57 Trust Fund	87-0640888	At least 80%	At least 80%	At least 80%	None	None	$	7	$	8	$	8	2015, 2014, 2013

(1) PacifiCorp's and Energy West Mining Company's minimum contributions to the plans are based on the amount of wages paid to employees covered by the Local 57 Trust Fund collective bargaining agreements and the number of mining hours worked for the UMWA 1974 Pension Plan, respectively, subject to ERISA minimum funding requirements. As a result of the plan's critical status, Energy West Mining Company was required to begin paying a surcharge for hours worked on and after December 1, 2014.

(2) For the UMWA 1974 Pension Plan, information is for plan years beginning July 1, 2015, 2014 and 2013. Information for the plan year beginning July 1, 2016 is not yet available. For the Local 57 Trust Fund, information is for plan years beginning July 1, 2015, 2014 and 2013. Information for the plan year beginning July 1, 2016 is not yet available.

MidAmerican Energy Company [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

Net periodic benefit cost for the plans of MidAmerican Energy and the aforementioned affiliates included the following components for the years ended December 31 (in millions):

	Pension									Other Postretirement
	2017			2016			2015			2017			2016			2015
Service cost	$	9		$	10		$	12		$	5		$	5		$	7
Interest cost	31			34			32			9			10			9
Expected return on plan assets	(44		)	(44		)	(46		)	(14		)	(13		)	(15		)
Net amortization	2			2			2			(4		)	(4		)	(3		)
Net periodic benefit (credit) cost	$	(2	)	$	2		$	—		$	(4	)	$	(2	)	$	(2	)

Changes in Fair Value of Plan Assets [Table Text Block]

The following table is a reconciliation of the fair value of plan assets for the years ended December 31 (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Plan assets at fair value, beginning of year	$	684		$	678		$	252		$	249
Employer contributions	7			7			1			1
Participant contributions	—			—			1			1
Actual return on plan assets	114			57			36			14
Benefits paid	(60		)	(58		)	(13		)	(13		)
Plan assets at fair value, end of year	$	745		$	684		$	277		$	252

Changes in Projected Benefit Obligations [Table Text Block]

The following table is a reconciliation of the benefit obligations for the years ended December 31 (in millions):

	Pension						Other Postretirement
	2017			2016			2017			2016
Benefit obligation, beginning of year	$	773		$	785		$	233		$	234
Service cost	9			10			5			5
Interest cost	31			34			9			10
Participant contributions	—			—			1			1
Actuarial loss (gain)	46			2			11			(4		)
Benefits paid	(60		)	(58		)	(13		)	(13		)
Benefit obligation, end of year	$	799		$	773		$	246		$	233
Accumulated benefit obligation, end of year	$	790		$	764

Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]

The funded status of the plans and the amounts recognized on the Balance Sheets as of December 31 are as follows (in millions):

	Pension						Other Postretirement
	2017			2016			2017		2016
Plan assets at fair value, end of year	$	745		$	684		$	277	$	252
Less - Benefit obligation, end of year	799			773			246		233
Funded status	$	(54	)	$	(89	)	$	31	$	19
Amounts recognized on the Balance Sheets:
Other assets	$	66		$	26		$	31	$	19
Other current liabilities	(8		)	(8		)	—		—
Other liabilities	(112		)	(107		)	—		—
Amounts recognized	$	(54	)	$	(89	)	$	31	$	19

Net Periodic Benefit Costs Not Yet Recognized [Table Text Block]

The portion of the funded status of the plans not yet recognized in net periodic benefit cost as of December 31 is as follows (in millions):

	Pension					Other Postretirement
	2017			2016		2017			2016
Net (gain) loss	$	(11	)	$	15	$	23		$	36
Prior service cost (credit)	1			1		(25		)	(31		)
Total	$	(10	)	$	16	$	(2	)	$	5

A reconciliation of the amounts not yet recognized as components of net periodic benefit cost for the years ended December 31, 2017 and 2016 is as follows (in millions):

	Regulatory Asset			Regulatory Liability			Receivables (Payables) with Affiliates		Total
Pension
Balance, December 31, 2015	$	22		$	—		$	6	$	28
Net loss (gain) arising during the year	1			(11		)	—		(10		)
Net amortization	(1		)	(1		)	—		(2		)
Total	—			(12		)	—		(12		)
Balance, December 31, 2016	22			(12		)	6		16
Net loss (gain) arising during the year	4			(29		)	1		(24		)
Net amortization	(2		)	—			—		(2		)
Total	2			(29		)	1		(26		)
Balance, December 31, 2017	$	24		$	(41	)	$	7	$	(10	)

	Regulatory Asset			Receivables (Payables) with Affiliates			Total
Other Postretirement
Balance, December 31, 2015	$	17		$	(11	)	$	6
Net gain arising during the year	(2		)	(3		)	(5		)
Net amortization	3			1			4
Total	1			(2		)	(1		)
Balance, December 31, 2016	18			(13		)	5
Net gain arising during the year	(7		)	(4		)	(11		)
Net amortization	3			1			4
Total	(4		)	(3		)	(7		)
Balance, December 31, 2017	$	14		$	(16	)	$	(2	)

Defined Benefit Plans, Amounts To Be Recognized In Following Year [Table Text Block]

The net loss and prior service cost (credit) that will be amortized in 2018 into net periodic benefit cost are estimated to be as follows (in millions):

	Net Loss		Prior Service Cost (Credit)			Total
Pension	$	1	$	1		$	2
Other postretirement	1		(5		)	(4		)
Total	$	2	$	(4	)	$	(2	)

Plan Assumptions [Table Text Block]

Assumptions used to determine benefit obligations and net periodic benefit cost were as follows:

	Pension						Other Postretirement
	2017		2016		2015		2017		2016		2015
Benefit obligations as of December 31:
Discount rate	3.60	%	4.10	%	4.50	%	3.50	%	3.90	%	4.25	%
Rate of compensation increase	2.75	%	2.75	%	2.75	%	N/A		N/A		N/A
Net periodic benefit cost for the years ended December 31:
Discount rate	4.10	%	4.50	%	4.00	%	3.90	%	4.25	%	3.75	%
Expected return on plan assets(1)	6.75	%	7.00	%	7.25	%	6.50	%	6.75	%	7.00	%
Rate of compensation increase	2.75	%	2.75	%	2.75	%	N/A		N/A		N/A

(1) Amounts reflected are pre-tax values. Assumed after-tax returns for a taxable, non-union other postretirement plan were 4.81% for 2017, and 5.00% for 2016, and 5.18% for 2015.

In establishing its assumption as to the expected return on plan assets, MidAmerican Energy utilizes the asset allocation and return assumptions for each asset class based on historical performance and forward-looking views of the financial markets.

	2017		2016
Assumed healthcare cost trend rates as of December 31:
Healthcare cost trend rate assumed for next year	7.10	%	7.40	%
Rate that the cost trend rate gradually declines to	5.00	%	5.00	%
Year that the rate reaches the rate it is assumed to remain at	2025		2025

Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]

A one percentage-point change in assumed healthcare cost trend rates would have the following effects (in millions):

	One Percentage-Point
	Increase		Decrease
Increase (decrease) in:
Total service and interest cost for the year ended December 31, 2017	$	—	$	—
Other postretirement benefit obligation as of December 31, 2017	3		(3		)

Expected Benefit Payments [Table Text Block]

Net periodic benefit costs assigned to MidAmerican Energy affiliates are reimbursed currently in accordance with its intercompany administrative services agreement. The expected benefit payments to participants in MidAmerican Energy's pension and other postretirement benefit plans for 2017 through 2021 and for the five years thereafter are summarized below (in millions):

	Projected Benefit Payments
	Pension		Other Postretirement
2018	$	60	$	19
2019	61		20
2020	60		21
2021	59		22
2022	57		21
2023-2027	256		98

Allocation of Plan Assets [Table Text Block]

The target allocations (percentage of plan assets) for MidAmerican Energy's pension and other postretirement benefit plan assets are as follows as of December 31, 2017:

	Pension	Other Postretirement
	%	%
Debt securities(1)	20-50	25-45
Equity securities(1)	60-80	45-80
Real estate funds	2-8	—
Other	0-3	0-5

(1) For purposes of target allocation percentages and consistent with the plans' investment policy, investment funds are allocated based on the underlying investments in debt and equity securities.

Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following table presents the fair value of plan assets, by major category, for MidAmerican Energy's defined benefit pension plan (in millions):

	Input Levels for Fair Value Measurements(1)
	Level 1		Level 2		Level 3		Total
As of December 31, 2017:
Cash equivalents	$	—	$	17	$	—	$	17
Debt securities:
United States government obligations	21		—		—		21
Corporate obligations	—		59		—		59
Municipal obligations	—		7		—		7
Agency, asset and mortgage-backed obligations	—		33		—		33
Equity securities:
United States companies	137		—		—		137
International equity securities	44		—		—		44
Investment funds(2)	74		—		—		74
Total assets in the hierarchy	$	276	$	116	$	—	392
Investment funds(2) measured at net asset value							315
Real estate funds measured at net asset value							38
Total assets measured at fair value							$	745
As of December 31, 2016:
Cash equivalents	$	—	$	17	$	—	$	17
Debt securities:
United States government obligations	9		—		—		9
Corporate obligations	—		53		—		53
Municipal obligations	—		6		—		6
Agency, asset and mortgage-backed obligations	—		22		—		22
Equity securities:
United States companies	130		—		—		130
International equity securities	39		—		—		39
Investment funds(2)	63		—		—		63
Total assets in the hierarchy	$	241	$	98	$	—	339
Investment funds(2) measured at net asset value							295
Real estate funds measured at net asset value							50
Total assets measured at fair value							$	684

(1) Refer to Note 14 for additional discussion regarding the three levels of the fair value hierarchy.

(2) Investment funds are comprised of mutual funds and collective trust funds. These funds consist of equity and debt securities of approximately 69% and 31%, respectively, for 2017 and 74% and 26%, respectively, for 2016. Additionally, these funds are invested in United States and international securities of approximately 72% and 28%, respectively, for 2017 and 71% and 29%, respectively, for 2016.

The following table presents the fair value of plan assets, by major category, for MidAmerican Energy's defined benefit other postretirement plans (in millions):

	Input Levels for Fair Value Measurements(1)
	Level 1		Level 2		Level 3		Total
As of December 31, 2017:
Cash equivalents	$	6	$	—	$	—	$	6
Debt securities:
United States government obligations	5		—		—		5
Corporate obligations	—		14		—		14
Municipal obligations	—		44		—		44
Agency, asset and mortgage-backed obligations	—		12		—		12
Equity securities:
United States companies	84		—		—		84
Investment funds(2)	112		—		—		112
Total assets measured at fair value	$	207	$	70	$	—	$	277
As of December 31, 2016:
Cash equivalents	$	10	$	—	$	—	$	10
Debt securities:
United States government obligations	5		—		—		5
Corporate obligations	—		11		—		11
Municipal obligations	—		37		—		37
Agency, asset and mortgage-backed obligations	—		11		—		11
Equity securities:
United States companies	122		—		—		122
Investment funds(2)	56		—		—		56
Total assets measured at fair value	$	193	$	59	$	—	$	252

(1) Refer to Note 14 for additional discussion regarding the three levels of the fair value hierarchy.

(2) Investment funds are comprised of mutual funds and collective trust funds. These funds consist of equity and debt securities of approximately 81% and 19%, respectively, for 2017 and 70% and 30%, respectively, for 2016. Additionally, these funds are invested in United States and international securities of approximately 42% and 58%, respectively, for 2017 and 30% and 70%, respectively, for 2016.

The following table presents MidAmerican Energy's assets and liabilities recognized on the Balance Sheets and measured at fair value on a recurring basis (in millions):

	Input Levels for Fair Value Measurements
	Level 1		Level 2			Level 3			Other(1)			Total
As of December 31, 2017:
Assets:
Commodity derivatives	$	—	$	3		$	4		$	(2	)	$	5
Money market mutual funds(2)	133		—			—			—			133
Debt securities:
United States government obligations	176		—			—			—			176
International government obligations	—		5			—			—			5
Corporate obligations	—		36			—			—			36
Municipal obligations	—		2			—			—			2
Equity securities:
United States companies	288		—			—			—			288
International companies	7		—			—			—			7
Investment funds	15		—			—			—			15
	$	619	$	46		$	4		$	(2	)	$	667
Liabilities - commodity derivatives	$	—	$	(9	)	$	(1	)	$	2		$	(8	)
As of December 31, 2016
Assets:
Commodity derivatives	$	—	$	9		$	1		$	(2	)	$	8
Money market mutual funds(2)	1		—			—			—			1
Debt securities:
United States government obligations	161		—			—			—			161
International government obligations	—		3			—			—			3
Corporate obligations	—		36			—			—			36
Municipal obligations	—		2			—			—			2
Agency, asset and mortgage-backed obligations	—		2			—			—			2
Equity securities:
United States companies	250		—			—			—			250
International companies	5		—			—			—			5
Investment funds	9		—			—			—			9
	$	426	$	52		$	1		$	(2	)	$	477
Liabilities - commodity derivatives	$	—	$	(3	)	$	(3	)	$	3		$	(3	)

(1) Represents netting under master netting arrangements and a net cash collateral receivable of $- million and $1 million as of December 31, 2017 and 2016, respectively.

(2) Amounts are included in cash and cash equivalents and investments and restricted cash and investments on the Balance Sheets. The fair value of these money market mutual funds approximates cost.

MidAmerican Funding, LLC and Subsidiaries [Domain]

Defined Benefit Plan Disclosure [Line Items]

Schedule of Net Benefit Costs [Table Text Block]

Pension and postretirement costs allocated by MidAmerican Funding to its parent and other affiliates in each of the years ended December 31, were as follows (in millions):

	2017			2016			2015
Pension costs	$	4		$	4		$	4
Other postretirement costs	(3		)	(1		)	(2		)