Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]
Net income	$ 112,294	$ 78,800	$ 103,539
Other Comprehensive Income (Loss):
Unrealized investment gains/(losses) - net of taxes of $(1,026), $191 and $77, respectively	(1,741)	323	134
Reclassification adjustment for realized gains on investment securities included in net income - net of taxes of $(7) and $(171), respectively	(12)	(290)	0
Change in unfunded benefit obligation for pension and other postretirement benefit plans - net of taxes of $1,418, $(590) and $(778), respectively	2,634	(1,096)	(1,445)
Total other comprehensive income (loss)	881	(1,063)	(1,311)
Comprehensive income	113,175	77,737	102,228
Comprehensive income attributable to noncontrolling interests	(1,217)	(590)	(3,315)
Comprehensive income attributable to Avista Corporation shareholders	$ 111,958	$ 77,147	$ 98,913