Subsidiary Debt Subsidiary Debt - AltaLink (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Par value		$ 36,295
Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value		27,476
Other long-term debt		27,354	$ 27,214
ALP Investments [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	[1]	447
Other long-term debt		453	556
ALP Investments [Member] | Subsidiary Debt [Member] | Series 09-1 Senior Bonds, 5.207%, due 2016 [Member]
Debt Instrument [Line Items]
Par value	[1]	0
Other long-term debt		$ 0	$ 112
Debt Instrument, Interest Rate, Stated Percentage		5.207%	5.207%
ALP Investments [Member] | Subsidiary Debt [Member] | Series 12-1 Senior Bonds, 3.674%, due 2019 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 149
Other long-term debt		$ 153	$ 151
Debt Instrument, Interest Rate, Stated Percentage		3.674%	3.674%
ALP Investments [Member] | Subsidiary Debt [Member] | Series 13-1 Senior Bonds, 3.265%, due 2020 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 149
Other long-term debt		$ 152	$ 149
Debt Instrument, Interest Rate, Stated Percentage		3.265%	3.265%
ALP Investments [Member] | Subsidiary Debt [Member] | Series 15-1 Senior Bonds, 2.244%, due 2022 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 149
Other long-term debt		$ 148	$ 144
Debt Instrument, Interest Rate, Stated Percentage		2.244%	2.244%
AltaLink, L.P. [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 3,608
Other long-term debt		3,592	$ 2,911
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2008-1 Notes, 5.243%, due 2018 [Member]
Debt Instrument [Line Items]
Par value	[1]	149
Other long-term debt		$ 148	$ 145
Debt Instrument, Interest Rate, Stated Percentage		5.243%	5.243%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2013-2 Notes, 3.621%, due 2020 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 93
Other long-term debt		$ 93	$ 90
Debt Instrument, Interest Rate, Stated Percentage		3.621%	3.621%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2012-2 Notes, 2.978%, due 2022 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 204
Other long-term debt		$ 204	$ 198
Debt Instrument, Interest Rate, Stated Percentage		2.978%	2.978%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2013-4 Notes, 3.668%, due 2023 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 372
Other long-term debt		$ 371	$ 360
Debt Instrument, Interest Rate, Stated Percentage		3.668%	3.668%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2014-1 Notes, 3.399%, due 2024 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 260
Other long-term debt		$ 260	$ 252
Debt Instrument, Interest Rate, Stated Percentage		3.399%	3.399%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2016-1 Notes, 2.747%, due 2026 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 260
Other long-term debt		$ 259	$ 0
Debt Instrument, Interest Rate, Stated Percentage		2.747%	0.00%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2006-1 Notes, 5.249%, due 2036 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 112
Other long-term debt		$ 111	$ 108
Debt Instrument, Interest Rate, Stated Percentage		5.249%	5.249%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2010-1 Notes, 5.381%, due 2040 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 93
Other long-term debt		$ 93	$ 90
Debt Instrument, Interest Rate, Stated Percentage		5.381%	5.381%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2010-2 Notes, 4.872%, due 2040 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 112
Other long-term debt		$ 111	$ 108
Debt Instrument, Interest Rate, Stated Percentage		4.872%	4.872%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2011-1 Notes, 4.462%, due 2041 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 205
Other long-term debt		$ 204	$ 198
Debt Instrument, Interest Rate, Stated Percentage		4.462%	4.462%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2012-1 Notes, 3.99%, due 2042 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 391
Other long-term debt		$ 385	$ 374
Debt Instrument, Interest Rate, Stated Percentage		3.99%	3.99%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2013-3 Notes, 4.922%, due 2043 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 260
Other long-term debt		$ 260	$ 252
Debt Instrument, Interest Rate, Stated Percentage		4.922%	4.922%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2014-3 Notes, 4.054%, due 2044 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 219
Other long-term debt		$ 218	$ 212
Debt Instrument, Interest Rate, Stated Percentage		4.054%	4.054%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2015-1 Notes, 4.090%, due 2045 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 260
Other long-term debt		$ 259	$ 251
Debt Instrument, Interest Rate, Stated Percentage		4.09%	4.09%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2016-2 Notes, 3.717%, due 2046 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 335
Other long-term debt		$ 333	$ 0
Debt Instrument, Interest Rate, Stated Percentage		3.717%	0.00%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2013-1 Notes, 4.446%, due 2053 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 186
Other long-term debt		$ 186	$ 180
Debt Instrument, Interest Rate, Stated Percentage		4.446%	4.446%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Series 2014-2 Notes, 4.274%, due 2064 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 97
Other long-term debt		$ 97	$ 93
Debt Instrument, Interest Rate, Stated Percentage		4.274%	4.274%
AltaLink, L.P. [Member] | Subsidiary Debt [Member] | Construction Loan, 4.950%, due 2021 [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 13
Other long-term debt		$ 13	$ 0
Debt Instrument, Interest Rate, Stated Percentage		4.95%	0.00%
BHE Transmission [Member] | Subsidiary Debt [Member]
Debt Instrument [Line Items]
Par value	[1]	$ 4,068
Other long-term debt		$ 4,058	$ 3,467

[1] (1)The par values for these debt instruments are denominated in Canadian dollars.