Stock-Based Compensation and Employee Benefit Plan - Stock-based Compensation Expense (Additional Information) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Share-based payment arrangement, amount capitalized	$ 0.8	$ 1.2

Share-based Payment Arrangement, Amount Capitalize

No definition available.

Name:	be_ShareBasedPaymentArrangementAmountCapitalize
Namespace Prefix:	be_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant