Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Revenues:
Utility Revenues Excluding Alternative Revenue Programs	$ 408,356	$ 445,573
Revenue from Alternative Revenue Programs	(5,939)	(15,036)
Utility revenues	402,417	430,537
Other non-utility revenues	6,944	5,933
Total operating revenues	409,361	436,470
Utility operating expenses:
Resource costs	154,618	165,586
Other operating expenses	77,298	72,443
Acquisition costs	672	0
Depreciation and amortization	44,733	41,985
Taxes other than income taxes	30,829	32,662
Other non-utility operating expenses:
Other operating expenses	6,824	6,179
Depreciation and amortization	181	188
Total operating expenses	315,155	319,043
Income from operations	94,206	117,427
Interest expense	24,776	23,545
Interest expense to affiliated trusts	253	185
Capitalized interest	(968)	(724)
Other income-net	4,479	(1,060)
Income before income taxes	65,666	95,481
Income tax expense	10,710	33,344
Net income	54,956	62,137
Net income attributable to noncontrolling interests	(66)	(21)
Net income attributable to Avista Corporation shareholders	$ 54,890	$ 62,116
Weighted-average common shares outstanding (thousands), basic	65,639	64,362
Weighted-average common shares outstanding (thousands), diluted	65,931	64,469
Earnings per common share attributable to Avista Corporation shareholders:
Basic	$ 0.84	$ 0.97
Diluted	0.83	0.96
Common Stock, Dividends, Per Share, Cash Paid	$ 0.3725	$ 0.3575