Regulatory Matters Regulatory Matters - NPC - Regulatory Assets (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Regulatory Assets [Line Items]
Total regulatory assets		$ 2,881	$ 3,067
Regulatory assets		115	171
Regulatory assets		2,766	2,896
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided		$ 1,400	1,300
Deferred Operating Costs
Regulatory Assets [Line Items]
Regulatory asset amortization period years		11
Total regulatory assets		$ 134	141
Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory asset amortization period years		Various
Total regulatory assets		$ 445	375
Abandoned projects
Regulatory Assets [Line Items]
Regulatory asset amortization period years		3.48275862068966
Total regulatory assets		$ 58	134
Nevada Power Company [Member]
Regulatory Assets [Line Items]
Total regulatory assets		801	917
Regulatory assets		1	39
Regulatory assets		800	878
Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided		$ 303	334
Nevada Power Company [Member] | Decommissioning costs
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period	[1]	3 years
Total regulatory assets	[1]	$ 241	222
Regulatory Assets, Amortization Period Unknown		$ 104	81
Nevada Power Company [Member] | Deferred Operating Costs
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		9 years
Total regulatory assets		$ 136	152
Nevada Power Company [Member] | Merger costs from 1999 merger
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		25 years
Total regulatory assets		$ 120	125
Nevada Power Company [Member] | Employee benefit plans
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period	[2]	8 years
Total regulatory assets	[2]	$ 87	105
Nevada Power Company [Member] | Asset retirement obligations
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		6 years
Total regulatory assets		$ 67	68
Nevada Power Company [Member] | Legacy meters
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		13 years
Total regulatory assets		$ 49	53
Nevada Power Company [Member] | ON Line deferrals
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		34 years
Total regulatory assets		$ 45	46
Nevada Power Company [Member] | Abandoned projects
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
Total regulatory assets		$ 12	46
Nevada Power Company [Member] | Deferred energy costs
Regulatory Assets [Line Items]
Regulatory Asset, Amortization Period		1 year
Total regulatory assets		$ 0	47
Nevada Power Company [Member] | Other
Regulatory Assets [Line Items]
Regulatory asset amortization period years		Various
Total regulatory assets		$ 44	$ 53

[1] Amount includes regulatory assets with an indeterminate life of $104 million and $81 million as of December 31, 2019 and 2018, respectively.

[2] Represents amounts not yet recognized as a component of net periodic benefit cost that are expected to be included in regulated rates when recognized.