Retirement Plan and Postretirement Benefits - NPC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 2	$ 8
Liability, Defined Benefit Plan, Noncurrent	7	13
Liability, Defined Benefit Plan, Current	0	0
UNITED STATES | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	12	38
Liability, Defined Benefit Plan, Noncurrent	282	329
Liability, Defined Benefit Plan, Current	13	13
Nevada Power Company [Member] | UNITED STATES | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	0	$ 0
Nevada Power Company [Member] | UNITED STATES | NV Energy, Inc. [Member] | Other Noncurrent Liabilities [Member] | Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Plan, Noncurrent	2	1
Nevada Power Company [Member] | Qualified Plan [Member] | UNITED STATES | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	19	1
Nevada Power Company [Member] | Qualified Plan [Member] | UNITED STATES | NV Energy, Inc. [Member] | Other Noncurrent Liabilities [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Plan, Noncurrent	18	26
Nevada Power Company [Member] | Nonqualified Plan [Member] | UNITED STATES | Other Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer	1	1	$ 1
Nevada Power Company [Member] | Nonqualified Plan [Member] | UNITED STATES | NV Energy, Inc. [Member] | Other Noncurrent Liabilities [Member] | Other Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Plan, Noncurrent	9	9
Nevada Power Company [Member] | Nonqualified Plan [Member] | UNITED STATES | NV Energy, Inc. [Member] | Other Current Liabilities [Member] | Other Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Liability, Defined Benefit Plan, Current	$ 1	$ 1