Employee Benefit Plans (Details) - NV Energy [Member] - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Qualified Pension Plans [Member]
Amounts Recognized in Balance Sheet [Abstract]
Other long-term liabilities	$ 13	$ 13
Non-Qualified Pension Plans [Member]
Amounts Recognized in Balance Sheet [Abstract]
Other long-term liabilities	10	10
Other current liabilities	1	1
Other Postretirement Plans [Member]
Amounts Recognized in Balance Sheet [Abstract]
Other long-term liabilities	$ 34	$ 33