Income Taxes - NPC - Summary of Operating Loss Carryforwards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Nevada Power Company [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 4
Deferred Tax Assets, Operating Loss Carryforwards	1
Deferred Tax Assets, Tax Credit Carryforwards	14
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	10,084	[1]
Deferred Tax Assets, Operating Loss Carryforwards	589
Deferred Tax Assets, Tax Credit Carryforwards	$ 31	[2]
Minimum [Member] | Nevada Power Company [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2031
Tax Credit Carryforward, Expiration Date	Dec. 31, 2016
Minimum [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2016
Tax Credit Carryforward, Expiration Date	Dec. 31, 2016
Maximum [Member] | Nevada Power Company [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2035
Tax Credit Carryforward, Expiration Date	Dec. 31, 2035
Maximum [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2035

[1] The federal net operating loss carry forwards relate principally to net operating loss carry forwards of subsidiaries that are tax residents in both the United States and the United Kingdom. The net operating loss carry forwards were generated prior to Berkshire Hathaway Inc.'s ownership and will begin to expire in 2022.

[2] Includes $102 million of deferred foreign tax credits associated with the federal income tax on unremitted tax earnings and profit pools that will begin to be creditable and expire 10 years after the date the foreign earnings are repatriated through actual or deemed dividends. As of December 31, 2015 the statute of limitation had not begun on the foreign tax credit carryforwards.