Subsidiary Debt Subsidiary Debt - NPC - Capital and Financial Lease Obligations (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Par value		$ 37,014
Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value		28,263
Other long-term debt		28,097	$ 28,641
Nevada Power Company [Member]
Debt Instrument [Line Items]
Par value		2,847
Total Long-term Debt and Capital and Financial Lease Obligations		2,816	3,075
Long-term Debt and Capital and Financial Lease Obligations, Current		520	842
Long-term Debt and Capital and Financial Lease Obligations		2,296	2,233
Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.500%, Series O due 2018 [Member]
Debt Instrument [Line Items]
Other long-term debt			324
Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.500%, Series S due 2018 [Member]
Debt Instrument [Line Items]
Other long-term debt			499
Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 7.125%, Series V due 2019 [Member]
Debt Instrument [Line Items]
Other long-term debt			499
Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.650%, Series N due 2036 [Member]
Debt Instrument [Line Items]
Other long-term debt		358	357
Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.750%, Series R due 2037 [Member]
Debt Instrument [Line Items]
Other long-term debt		346	346
Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.375%, Series X due 2040 [Member]
Debt Instrument [Line Items]
Other long-term debt		247	247
Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.450%, Series Y due 2041 [Member]
Debt Instrument [Line Items]
Other long-term debt		236	236
Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 2.750%, Series BB due 2020 [Member]
Debt Instrument [Line Items]
Other long-term debt		574	0
Nevada Power Company [Member] | Subsidiary Debt [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Other long-term debt			475
NV Energy [Member]
Debt Instrument [Line Items]
Par value		4,321
Other long-term debt		4,318	4,581
NV Energy [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value		4,321
Other long-term debt		4,318	4,581
NV Energy [Member] | Nevada Power Company [Member]
Debt Instrument [Line Items]
Par value		2,847
Other long-term debt		2,829	3,088
NV Energy [Member] | Nevada Power Company [Member] | Mortgage Securities, 6.500%, Series O due 2018 [Member]
Debt Instrument [Line Items]
Par value		0
Other long-term debt		0	324
NV Energy [Member] | Nevada Power Company [Member] | Mortgage Securities, 6.500%, Series S due 2018 [Member]
Debt Instrument [Line Items]
Par value		0
Other long-term debt		0	499
NV Energy [Member] | Nevada Power Company [Member] | Mortgage Securities, 7.125%, Series V due 2019 [Member]
Debt Instrument [Line Items]
Par value		500
Other long-term debt		500	499
NV Energy [Member] | Nevada Power Company [Member] | Mortgage Securities, 6.650%, Series N due 2036 [Member]
Debt Instrument [Line Items]
Par value		367
Other long-term debt		360	359
NV Energy [Member] | Nevada Power Company [Member] | Mortgage Securities, 6.750%, Series R due 2037 [Member]
Debt Instrument [Line Items]
Par value		349
Other long-term debt		348	348
NV Energy [Member] | Nevada Power Company [Member] | Mortgage Securities, 5.375%, Series X due 2040 [Member]
Debt Instrument [Line Items]
Par value		250
Other long-term debt		248	248
NV Energy [Member] | Nevada Power Company [Member] | Mortgage Securities, 5.450%, Series Y due 2041 [Member]
Debt Instrument [Line Items]
Par value		250
Other long-term debt		244	244
NV Energy [Member] | Nevada Power Company [Member] | Mortgage Securities, 2.750%, Series BB due 2020 [Member]
Debt Instrument [Line Items]
Par value		575
Other long-term debt		574	0
NV Energy [Member] | Nevada Power Company [Member] | NPC Pollution Control Refunding Revenue Bonds, 1.80%, Series 2017A, due 2032 [Member]
Debt Instrument [Line Items]
Par value	[1]	40
Other long-term debt	[1]	40	40
NV Energy [Member] | Nevada Power Company [Member] | NPC Pollution Control Refunding Revenue Bonds, 1.60%, Series 2017, Due 2036 [Member]
Debt Instrument [Line Items]
Par value	[1]	40
Other long-term debt	[1]	$ 39	$ 39
NV Energy [Member] | Nevada Power Company [Member] | NPC Pollution Control Refunding Revenue Bonds, 1.60%, Series 2017B, due 2039 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.60%	1.60%
Par value	[1]	$ 13
Other long-term debt	[1]	13	$ 13
NV Energy [Member] | Nevada Power Company [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Par value		463
Other long-term debt		$ 463	$ 475
NV Energy [Member] | Nevada Power Company [Member] | Minimum [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		2.75%	2.75%
NV Energy [Member] | Nevada Power Company [Member] | Maximum [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		11.60%	11.60%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.500%, Series O due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.50%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.500%, Series S due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			6.50%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 7.125%, Series V due 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		7.125%	7.125%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.650%, Series N due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.65%	6.65%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 6.750%, Series R due 2037 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.75%	6.75%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.375%, Series X due 2040 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.375%	5.375%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 5.450%, Series Y due 2041 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.45%	5.45%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Mortgage Securities, 2.750%, Series BB due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.75%	2.75%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | NPC Pollution Control Refunding Revenue Bonds, 1.80%, Series 2017A, due 2032 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.80%	1.80%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | NPC Pollution Control Refunding Revenue Bonds, 1.60%, Series 2017, Due 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.60%	1.60%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | NPC Pollution Control Refunding Revenue Bonds, 1.60%, Series 2017B, due 2039 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.60%	1.60%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Minimum [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		2.75%	2.75%
NV Energy [Member] | Nevada Power Company [Member] | Subsidiary Debt [Member] | Maximum [Member] | Capital lease obligations, 2.75% to 11.60%, due through 2054 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate		11.60%	11.60%
Land and Building [Member] | Nevada Power Company [Member]
Debt Instrument [Line Items]
Terms Of Capital Lease		20 years
Capital Leased Assets, Gross		$ 6	$ 0

[1] (1)Subject to mandatory purchase by Nevada Power in May 2020 at which date the interest rate may be adjusted from time to time.