Retirement Plan and Postretirement Benefits - SPPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
United States Pension Plan of US Entity [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer	$ 78	$ 13
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(438)	(437)
Other current liabilities	(15)	(15)
Sierra Pacific Power Company [Member] | United States Pension Plan of US Entity [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer	27	0	$ 0
Sierra Pacific Power Company [Member] | Nonqualified Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer	0	0	0
Sierra Pacific Power Company [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer	1	0	$ 0
Sierra Pacific Power Company [Member] | Other Noncurrent Liabilities [Member] | NV Energy, Inc. [Member] | United States Pension Plan of US Entity [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(12)	(29)
Sierra Pacific Power Company [Member] | Other Noncurrent Liabilities [Member] | NV Energy, Inc. [Member] | Nonqualified Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(9)	(9)
Sierra Pacific Power Company [Member] | Other Noncurrent Liabilities [Member] | NV Energy, Inc. [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(28)	(32)
Sierra Pacific Power Company [Member] | Other Current Liabilities [Member] | NV Energy, Inc. [Member] | Nonqualified Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other current liabilities	$ (1)	$ (1)