CONSOLIDATED BALANCE SHEETS (Unaudited) Parenthetical (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Current Assets:
Accounts receivable less allowance for uncollectible accounts	$ 31,297	$ 28,684
Shareholders' Equity:
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	350,000,000	350,000,000
Common stock, shares issued (in shares)	235,999,749	235,322,553
Common stock, shares outstanding (in shares)	235,999,749	235,322,553
Nevada Power Company [Member]
Current Assets:
Accounts receivable less allowance for uncollectible accounts	28,716	26,428
Shareholders' Equity:
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	1,000	1,000
Common stock, shares issued (in shares)	1,000	1,000
Common stock, shares outstanding (in shares)	1,000	1,000
Sierra Pacific Power Company [Member]
Current Assets:
Accounts receivable less allowance for uncollectible accounts	$ 2,581	$ 2,256
Shareholders' Equity:
Common stock, par value	$ 3.75	$ 3.75
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, shares issued (in shares)	1,000	1,000
Common stock, shares outstanding (in shares)	1,000	1,000