Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 137,316	$ 123,317	$ 192,277
Other Comprehensive Income (Loss):
Unrealized investment gains - net of taxes of $0, $0 and $664, respectively	0	0	1,126
Reclassification adjustment for realized gains on investment securities included in net income - net of taxes of $0, $0 and $(1), respectively	0	0	(2)
Reclassification adjustment for realized losses on investments, Net of Tax	0	0	462
Change in unfunded benefit obligation for pension and other postretirement benefit plans - net of taxes of $(495), $667 and $(1,967), respectively	(918)	1,238	(3,655)
Total other comprehensive income (loss)	(918)	1,238	(2,069)
Comprehensive income	136,398	124,555	190,208
Comprehensive income attributable to noncontrolling interests	(88)	(90)	(236)
Comprehensive income attributable to Avista Corporation shareholders	$ 136,310	$ 124,465	$ 189,972