Notes payable and other borrowings - Credit agreements - Narrative (Detail) - Line of Credit and Commercial Paper Facilities [Member] - Subsidiaries [Member] $ in Billions |
Dec. 31, 2018
USD ($)
|
|---|---|
| Line of Credit Facility [Line Items] | |
| Unused lines of credit available | $ 7.3 |
| Berkshire Hathaway Energy and Subsidiaries [Member] | |
| Line of Credit Facility [Line Items] | |
| Unused lines of credit available | $ 6.1 |