Consolidated Balance Sheets (Parenthetical) - NPC - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Common stock, shares authorized	115,000,000	115,000,000
Common stock, shares issued	77,000,000	77,000,000
Common stock, shares outstanding	77,000,000	77,000,000
Nevada Power Company [Member]
Common Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00
Common stock, shares authorized	1,000	1,000
Common stock, shares issued	1,000	1,000
Common stock, shares outstanding	1,000	1,000