Summary Of Significant Accounting Policies (Allowance For Doubtful Accounts) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Accounting Policies [Abstract]
Allowance as of the beginning of the year	$ 44,309		$ 44,155		$ 43,958
Additions expensed during the year	5,296		5,099		4,213
Net deductions (1)	(44,717)	[1]	(4,945)	[1]	(4,016)	[1]
Allowance as of the end of the year	$ 4,888		$ 44,309		$ 44,155

[1] During the second quarter of 2014, the Company received $15.0 million in gross proceeds related to the settlement of its California wholesale power markets litigation. The gross proceeds effectively settled all outstanding receivables and payables at Avista Energy (which had been fully reserved against since 2001). As a result of the settlement, the Company reversed $15.0 million of the allowance, which was recorded as a reduction to non-utility other operating expenses on the Consolidated Statements of Income, and the remainder of the receivables, payables and allowance were removed from the Consolidated Balance Sheets (and had no effect on net income). See Note 20 for additional discussion of the settlement in the California wholesale power markets litigation.