Subsidiary Debt - NV Energy (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Par value	$ 49,746
Subsidiary debt
Debt Instrument [Line Items]
Par value	36,545
Subsidiary debt	36,659	$ 36,319
NV Energy | Subsidiary debt
Debt Instrument [Line Items]
Par value	3,701
Subsidiary debt	3,675	3,673
NPC
Debt Instrument [Line Items]
Par value	2,534
Subsidiary debt	2,510	2,507
Eligible property subject to lien of mortgages	$ 9,400
NPC | Subsidiary debt | 3.700% Series CC, due 2029
Debt Instrument [Line Items]
Stated rate	3.70%
Par value	$ 500
Subsidiary debt	$ 497	496
NPC | Subsidiary debt | 2.400% Series DD, due 2030
Debt Instrument [Line Items]
Stated rate	2.40%
Par value	$ 425
Subsidiary debt	$ 422	422
NPC | Subsidiary debt | 6.650% Series N, due 2036
Debt Instrument [Line Items]
Stated rate	6.65%
Par value	$ 367
Subsidiary debt	$ 361	361
NPC | Subsidiary debt | 6.750% Series R, due 2037
Debt Instrument [Line Items]
Stated rate	6.75%
Par value	$ 349
Subsidiary debt	$ 347	347
NPC | Subsidiary debt | 5.375% Series X, due 2040
Debt Instrument [Line Items]
Stated rate	5.375%
Par value	$ 250
Subsidiary debt	$ 249	249
NPC | Subsidiary debt | 5.450% Series Y, due 2041
Debt Instrument [Line Items]
Stated rate	5.45%
Par value	$ 250
Subsidiary debt	$ 246	244
NPC | Subsidiary debt | 3.125% Series EE, due 2050
Debt Instrument [Line Items]
Stated rate	3.125%
Par value	$ 300
Subsidiary debt	$ 297	297
NPC | Subsidiary debt | 1.875% Pollution Control Bonds Series 2017A, due 2032
Debt Instrument [Line Items]
Stated rate	1.875%
Par value	$ 40
Subsidiary debt	$ 39	39
NPC | Subsidiary debt | 1.650% Pollution Control Bonds Series 2017, due 2036
Debt Instrument [Line Items]
Stated rate	1.65%
Par value	$ 40
Subsidiary debt	$ 39	39
NPC | Subsidiary debt | 1.650% Pollution Control Bonds Series 2017B, due 2039
Debt Instrument [Line Items]
Stated rate	1.65%
Par value	$ 13
Subsidiary debt	13	13
SPPC
Debt Instrument [Line Items]
Eligible property subject to lien of mortgages	4,500
SPPC | Subsidiary debt
Debt Instrument [Line Items]
Par value	1,167
Subsidiary debt	$ 1,165	1,166
SPPC | Subsidiary debt | 3.375% Series T, due 2023
Debt Instrument [Line Items]
Stated rate	3.375%
Par value	$ 250
Subsidiary debt	$ 249	249
SPPC | Subsidiary debt | 2.600% Series U, due 2026
Debt Instrument [Line Items]
Stated rate	2.60%
Par value	$ 400
Subsidiary debt	$ 397	397
SPPC | Subsidiary debt | 6.750% Series P, due 2037
Debt Instrument [Line Items]
Stated rate	6.75%
Par value	$ 252
Subsidiary debt	$ 254	256
SPPC | Subsidiary debt | 1.850% Pollution Control Series 2016B, due 2029
Debt Instrument [Line Items]
Stated rate	1.85%
Par value	$ 30
Subsidiary debt	$ 30	29
SPPC | Subsidiary debt | 3.000% Gas and Water Series 2016B, due 2036
Debt Instrument [Line Items]
Stated rate	3.00%
Par value	$ 60
Subsidiary debt	$ 60	61
SPPC | Subsidiary debt | 0.625% Water Facilities Series 2016C, due 2036
Debt Instrument [Line Items]
Stated rate	0.625%
Par value	$ 30
Subsidiary debt	$ 30	30
SPPC | Subsidiary debt | 2.050% Water Facilities Series 2016D, due 2036
Debt Instrument [Line Items]
Stated rate	2.05%
Par value	$ 25
Subsidiary debt	$ 25	25
SPPC | Subsidiary debt | 2.050% Water Facilities Series 2016E, due 2036
Debt Instrument [Line Items]
Stated rate	2.05%
Par value	$ 25
Subsidiary debt	$ 25	25
SPPC | Subsidiary debt | 2.050% Water Facilities Series 2016F, due 2036
Debt Instrument [Line Items]
Stated rate	2.05%
Par value	$ 75
Subsidiary debt	$ 75	74
SPPC | Subsidiary debt | 1.850% Water Facilities Series 2016G, due 2036
Debt Instrument [Line Items]
Stated rate	1.85%
Par value	$ 20
Subsidiary debt	$ 20	$ 20