Retirement Plan and Postretirement Benefits - NPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	$ 437	$ 399
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	15	14
Defined Benefit Plan, Contributions by Employer	13	37
Nevada 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	0	0	$ 0
Nevada 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
Nevada 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	0	0	$ 0
Nevada Power Company [Member] | NV Energy, Inc. [Member] | Other Noncurrent Liabilities [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	38	23
Nevada Power Company [Member] | NV Energy, Inc. [Member] | Other Noncurrent Liabilities [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
Nevada Power Company [Member] | NV Energy, Inc. [Member] | Other Noncurrent Liabilities [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	5	1
Nevada Power Company [Member] | NV Energy, Inc. [Member] | Other Current Liabilities [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, Current Liabilities	$ 1	$ 1