Balance Sheet Components Balance Sheet Components (Tables)

6 Months Ended

Jun. 30, 2018

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 June 30, 2018 and December 31, 2017 (dollars in thousands):



	June 30,		December 31,
	2018		2017
Materials and supplies	$	44,335	$	41,493
Fuel stock	5,958		4,843
Stored natural gas	6,608		11,739
Total	$	56,901	$	58,075

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

Net utility property consisted of the following as of June 30, 2018 and December 31, 2017 (dollars in thousands):



	June 30,		December 31,
	2018		2017
Utility plant in service	$	5,965,811	$	5,853,308
Construction work in progress	185,650		157,839
Total	6,151,461		6,011,147
Less: Accumulated depreciation and amortization	1,665,763		1,612,337
Total net utility property	$	4,485,698	$	4,398,810

Other Current Liabilities [Table Text Block]

Other current liabilities consisted of the following as of June 30, 2018 and December 31, 2017 (dollars in thousands):



	June 30,		December 31,
	2018		2017
Accrued taxes other than income taxes	$	34,951	$	33,802
Current unsettled interest rate swap derivative liabilities	—		34,447
Employee paid time off accruals	20,538		20,330
Accrued interest	16,659		16,351
Current portion of pensions and other postretirement benefits	10,376		11,544
Utility energy commodity derivative liabilities	7,789		8,848
Other current liabilities	31,101		33,791
Total other current liabilities	$	121,414	$	159,113

Schedule Of Regulated Asset And Liability [Table Text Block]

Regulatory assets and liabilities consisted of the following as of June 30, 2018 and December 31, 2017 (dollars in thousands):



	June 30, 2018				December 31, 2017
	Current		Non-Current		Current		Non-Current
Regulatory Assets
Energy commodity derivatives	$	21,750	$	11,277	$	24,991	$	18,967
Decoupling surcharge	5,571		13,308		19,759		2,600
Pension and other postretirement benefit plans	—		204,129		—		209,115
Interest rate swaps	—		134,078		—		169,704
Deferred income taxes	—		91,925		—		90,315
Settlement with Coeur d'Alene Tribe	—		43,299		—		43,954
Demand side management programs	—		21,932		—		24,620
Utility plant to be abandoned	—		23,773		—		24,330
Other regulatory assets	83		37,774		—		35,794
Total regulatory assets	$	27,404	$	581,495	$	44,750	$	619,399

Regulatory Liabilities
Income tax related liabilities	$	26,512	$	428,825	$	—	$	460,542
Deferred natural gas costs	31,515		—		37,474		—
Deferral power costs	9,160		34,212		5,816		24,057
Utility plant retirement costs	—		290,568		—		285,786
Interest rate swaps	—		30,994		—		18,638
Other regulatory liabilities	21,313		15,062		4,974		11,066
Total regulatory liabilities	$	88,500	$	799,661	$	48,264	$	800,089