Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Appropriated Retained Earnings [Table Text Block]

The appropriated retained earnings amounts included in retained earnings were as follows as of December 31 (dollars in thousands):



	2018		2017
Appropriated retained earnings	$	39,346	$	33,917

Schedule of Goodwill [Table Text Block]

There were no changes in the carrying amount of goodwill during 2017 and 2018 and the balance was as follows (dollars in thousands):



	AEL&P		Other		Accumulated Impairment Losses			Total
Balance as of December 31, 2017 and 2018	$	52,426	$	12,979	$	(7,733	)	$	57,672

Accumulated impairment losses are attributable to the other businesses.

Regulatory Liability For Utility Plant Retirement Costs [Table Text Block]

The Company has recorded the amount of estimated retirement costs collected from customers (that do not represent legal or contractual obligations) and included them as a non-current regulatory liability on the Consolidated Balance Sheets in the following amounts as of December 31 (dollars in thousands):



	2018		2017
Regulatory liability for utility plant retirement costs	$	297,379	$	285,786

Schedule of Inventory, Current [Table Text Block]

Inventories of materials and supplies, fuel stock and stored natural gas are recorded at average cost for our regulated operations and the lower of cost or market for our non-regulated operations and consisted of the following as of December 31 (dollars in thousands):



	2018		2017
Materials and supplies	$	47,403	$	41,493
Fuel stock	4,869		4,843
Stored natural gas	11,609		11,739
Total	$	63,881	$	58,075

Allowance for Credit Losses on Financing Receivables [Table Text Block]

The following table presents the activity in the allowance for doubtful accounts during the years ended December 31 (dollars in thousands):



	2018			2017			2016
Allowance as of the beginning of the year	$	5,132		$	5,026		$	4,530
Additions expensed during the year	3,917			5,317			6,053
Net deductions	(3,816		)	(5,211		)	(5,557		)
Allowance as of the end of the year	$	5,233		$	5,132		$	5,026

Schedule of Other Nonoperating Income (Expense) [Table Text Block]

Other Expense (Income) - net consisted of the following items for the years ended December 31 (dollars in thousands):



	2018			2017			2016
Interest income	$	(2,710	)	$	(2,162	)	$	(1,823	)
Interest on regulatory deferrals	(990		)	(1,288		)	(1,308		)
Equity-related AFUDC	(6,554		)	(6,669		)	(8,475		)
Non-service portion of pension and other postretirement benefit expenses	5,156			7,670			10,058
Net loss on investments	5,369			4,160			2,152
Other expense (income)	1,187			(1,104		)	(624		)
Total	$	1,458		$	607		$	(20	)

Share-based Compensation, Activity [Table Text Block]

The following table summarizes the number of grants, vested and unvested shares, earned shares (based on market metrics), and other pertinent information related to the Company's stock compensation awards for the years ended December 31:



	2018			2017			2016
Restricted Shares
Shares granted during the year	40,661			57,746			58,610
Shares vested during the year	(53,352		)	(57,473		)	(52,385		)
Unvested shares at end of year	91,998			106,053			109,806
Unrecognized compensation expense at end of year (in thousands)	$	1,964		$	1,853		$	1,853
TSR Awards
TSR shares granted during the year	80,724			114,390			116,435
TSR shares vested during the year	(107,342		)	(107,649		)	(111,665		)
TSR shares earned based on market metrics	—			158,262			132,887
Unvested TSR shares at end of year	187,172			218,507			222,228
Unrecognized compensation expense (in thousands)	$	3,706		$	2,849		$	3,409
CEPS Awards
CEPS shares granted during the year	40,329			57,223			57,521
CEPS shares vested during the year	(53,699		)	(53,862		)	(55,835		)
CEPS shares earned based on market metrics	30,102			41,502			90,460
Unvested CEPS shares at end of year	93,579			108,581			110,452
Unrecognized compensation expense (in thousands)	$	1,260		$	1,856		$	1,671

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

The Company recorded stock-based compensation expense (included in other operating expenses) and income tax benefits in the Consolidated Statements of Income of the following amounts for the years ended December 31 (dollars in thousands):



	2018		2017		2016
Stock-based compensation expense	$	5,367	$	7,359	$	7,891
Income tax benefits (1)	1,127		2,576		2,762
Excess tax benefits on settled share-based employee payments	990		2,348		1,597

Effective Rate On Allowance For Funds Used During Construction [Table Text Block]

The effective AFUDC rate was the following for the years ended December 31:



	2018		2017		2016
Avista Utilities
Effective AFUDC rate	7.43	%	7.29	%	7.29	%
Alaska Electric Light and Power Company
Effective AFUDC rate	9.04	%	9.48	%	9.40	%

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

For utility operations, the ratio of depreciation provisions to average depreciable property was as follows for the years ended December 31:



	2018		2017		2016
Avista Utilities
Ratio of depreciation to average depreciable property	3.17	%	3.12	%	3.11	%
Alaska Electric Light and Power Company
Ratio of depreciation to average depreciable property	2.46	%	2.43	%	2.39	%

The average service lives for the following broad categories of utility plant in service are (in years):



	Avista Utilities	Alaska Electric Light and Power Company
Electric thermal/other production	41	41
Hydroelectric production	78	44
Electric transmission	58	41
Electric distribution	35	40
Natural gas distribution property	46	N/A
Other shorter-lived general plant	10	16

Net Utility Property

Net utility property consisted of the following as of December 31 (dollars in thousands):



	2018		2017
Utility plant in service	$	6,209,968	$	5,853,308
Construction work in progress	160,598		157,839
Total	6,370,566		6,011,147
Less: Accumulated depreciation and amortization	1,721,636		1,612,337
Total net utility property	$	4,648,930	$	4,398,810

Gross Property, Plant and Equipment

The gross balances of the major classifications of property, plant and equipment are detailed in the following table as of December 31 (dollars in thousands):



	2018		2017
Avista Utilities:
Electric production	$	1,426,961	$	1,392,017
Electric transmission	761,156		726,240
Electric distribution	1,726,410		1,617,451
Electric construction work-in-progress (CWIP) and other	341,041		322,144
Electric total	4,255,568		4,057,852
Natural gas underground storage	48,549		46,233
Natural gas distribution	1,118,720		1,027,197
Natural gas CWIP and other	76,488		63,803
Natural gas total	1,243,757		1,137,233
Common plant (including CWIP)	641,465		588,833
Total Avista Utilities	6,140,790		5,783,918
AEL&P:
Electric production	99,803		97,883
Electric transmission	21,347		21,413
Electric distribution	22,374		21,061
Electric production held under long-term capital lease	71,007		71,007
Electric CWIP and other	7,072		7,341
Electric total	221,603		218,705
Common plant	8,173		8,524
Total AEL&P	229,776		227,229
Total gross utility property	6,370,566		6,011,147
Other (1)	39,145		36,783
Total	$	6,409,711	$	6,047,930


(1)	Included in other property and investments-net and other non-current assets on the Consolidated Balance Sheets. Accumulated depreciation was $12.4 million as of December 31, 2018 and $11.6 million as of December 31, 2017 for the other businesses.