Accounting For Income Taxes (Tables)

12 Months Ended

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense

	2013		2012		2011
Taxes currently provided	$	39,698	$	19,812	$	32,625
Deferred income tax expense	23,532		21,449		24,007
Total income tax expense	$	63,230	$	41,261	$	56,632

Schedule of Effective Income Tax Rate Reconciliation

	2013			2012			2011
Federal income taxes at statutory rates	$	61,433		$	42,021		$	56,060
Increase (decrease) in tax resulting from:
Tax effect of regulatory treatment of utility plant differences	3,532			2,432			1,798
State income tax expense	1,967			985			687
Settlement of prior year tax returns and adjustment of tax reserves	(1,104		)	(2,198		)	163
Manufacturing deduction	(2,033		)	(1,100		)	(1,099		)
Other	(565		)	(879		)	(977		)
Total income tax expense	$	63,230		$	41,261		$	56,632

Schedule of Deferred Income Tax Assets and Liabilities

	2013		2012
Deferred income tax assets:
Allowance for doubtful accounts	$	12,202	$	12,140
Reserves not currently deductible	6,322		5,923
Net operating loss from subsidiary acquisition	9,258		11,136
Deferred compensation	3,676		3,631
Unfunded benefit obligation	42,230		94,891
Utility energy commodity derivatives	13,303		22,953
Power and natural gas deferrals	9,226		12,490
Tax credits	11,365		19,401
Other	29,133		19,291
Total deferred income tax assets	136,715		201,856
Deferred income tax liabilities:
Intangible assets from subsidiary acquisition	4,271		5,582
Differences between book and tax basis of utility plant	521,238		494,579
Regulatory asset for pensions and other postretirement benefits	54,945		107,243
Power exchange contract	5,484		10,753
Utility energy commodity derivatives	13,305		22,954
Loss on reacquired debt	5,732		6,751
Interest rate swaps	15,097		12,308
Settlement with Coeur d’Alene Tribe	13,190		13,448
Other	14,008		18,227
Total deferred income tax liabilities	647,270		691,845
Net deferred income tax liability	$	510,555	$	489,989
Consolidated balance sheet classification of net deferred income taxes:
Current deferred income tax asset	$	24,788	$	34,281
Ecova long-term deferred income tax asset (1)	—		607
Long-term deferred income tax liability	535,343		524,877
Net deferred income tax liability	$	510,555	$	489,989

Schedule of Recovery of Deferred Income Tax Liabilities

	2013		2012
Regulatory assets for deferred income taxes	$	71,421	$	79,406