Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 123,317	$ 192,277	$ 112,294
Other Comprehensive Income (Loss):
Unrealized investment gains/(losses) - net of taxes of $0, $664 and $(1,026), respectively	0	1,126	(1,741)
Reclassification adjustment for realized gains on investment securities included in net income - net of taxes of $0, $(1) and $(7), respectively	0	(2)	(12)
Reclassification adjustment for realized losses on investments, Net of Tax	0	462	0
Change in unfunded benefit obligation for pension and other postretirement benefit plans - net of taxes of $667, $(1,967) and $1,418, respectively	1,238	(3,655)	2,634
Total other comprehensive income (loss)	1,238	(2,069)	881
Comprehensive income	124,555	190,208	113,175
Comprehensive income attributable to noncontrolling interests	(90)	(236)	(1,217)
Comprehensive income attributable to Avista Corporation shareholders	$ 124,465	$ 189,972	$ 111,958