CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current Assets:
Allowance for Doubtful Accounts Receivable, Current	$ 9,750	$ 8,150
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	350,000,000	350,000,000
Common stock, shares issued (in shares)	235,999,750	235,999,750
Common stock, shares outstanding (in shares)	235,747,750	235,999,750
treasurystockshares	252,000	0
Nevada Power Company [Member]
Current Assets:
Allowance for Doubtful Accounts Receivable, Current	8,514	6,751
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common Stock, Par or Stated Value Per Share	$ 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:
Allowance for Doubtful Accounts Receivable, Current	$ 1,236	$ 1,399
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common Stock, Par or Stated Value Per Share	$ 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