Selected Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2015

Selected Quarterly Financial Information [Abstract]

Summary of Quarterly Operations

	Three Months Ended
	March 31			June 30			September 30			December 31
2015
Operating revenues from continuing operations	$	446,490		$	337,332		$	313,649		$	387,305
Operating expenses from continuing operations	356,915			279,972			277,737			316,938
Income from continuing operations	$	89,575		$	57,360		$	35,912		$	70,367
Net income from continuing operations	$	46,462		$	25,078		$	12,754		$	33,876
Net income from discontinued operations	—			196			289			4,662
Net income	46,462			25,274			13,043			38,538
Net income attributable to noncontrolling interests	(13		)	(28		)	(32		)	(17		)
Net income attributable to Avista Corporation shareholders	$	46,449		$	25,246		$	13,011		$	38,521
Amounts attributable to Avista Corp. shareholders:
Net income from continuing operations attributable to Avista Corp. shareholders	$	46,449		$	25,050		$	12,722		$	33,859
Net income from discontinued operations attributable to Avista Corp. shareholders	—			196			289			4,662
Net income attributable to Avista Corp. shareholders	$	46,449		$	25,246		$	13,011		$	38,521
Outstanding common stock:
Weighted average, basic	62,318			62,281			62,299			62,308
Weighted average, diluted	62,889			62,600			62,688			62,758
Earnings per common share attributable to Avista Corp. shareholders, diluted:
Earnings per common share from continuing operations	$	0.74		$	0.40		$	0.21		$	0.54
Earnings per common share from discontinued operations	—			—			—			0.07
Total earnings per common share attributable to Avista Corp. shareholders, diluted	$	0.74		$	0.40		$	0.21		$	0.61

	Three Months Ended
	March 31			June 30		September 30			December 31
2014
Operating revenues from continuing operations	$	446,578		$	312,580	$	301,558		$	411,846
Operating expenses from continuing operations	356,236			249,849		268,796			345,093
Income from continuing operations	$	90,342		$	62,731	$	32,762		$	66,753
Net income from continuing operations	$	47,466		$	31,270	$	10,526		$	30,604
Net income (loss) from discontinued operations	1,515			69,312		(55		)	1,639
Net income	48,981			100,582		10,471			32,243
Net loss (income) attributable to noncontrolling interests	(482		)	289		(20		)	(23		)
Net income attributable to Avista Corporation shareholders	$	48,499		$	100,871	$	10,451		$	32,220
Amounts attributable to Avista Corp. shareholders:
Net income from continuing operations attributable to Avista Corp. shareholders	$	47,476		$	31,254	$	10,506		$	30,581
Net income (loss) from discontinued operations attributable to Avista Corp. shareholders	1,023			69,617		(55		)	1,639
Net income attributable to Avista Corp. shareholders	$	48,499		$	100,871	$	10,451		$	32,220
Outstanding common stock:
Weighted average, basic	60,122			60,184		63,934			62,290
Weighted average, diluted	60,168			60,463		64,244			62,671
Earnings per common share attributable to Avista Corp. shareholders, diluted:
Earnings per common share from continuing operations	$	0.79		$	0.52	$	0.16		$	0.48
Earnings per common share from discontinued operations	0.02			1.15		—			0.03
Total earnings per common share attributable to Avista Corp. shareholders, diluted	$	0.81		$	1.67	$	0.16		$	0.51