Debt Covenant, Minimum Debt Service Reserves Required

No definition available.

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

- Definition

Debt Instrument, Number Of Lenders

+ References

No definition available.

+ Details

Name:	be_DebtInstrumentNumberOfLenders
Namespace Prefix:	be_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Proceeds Used For Debt Service Reserves And Issuance Costs

+ References

No definition available.

+ Details

Name:	be_DebtProceedsUsedForDebtServiceReservesAndIssuanceCosts
Namespace Prefix:	be_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Debt Used To Fund Remaining System Purchases

+ References

No definition available.

+ Details

Name:	be_DebtUsedToFundRemainingSystemPurchases
Namespace Prefix:	be_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=be_PowerPurchaseAgreementCompany2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=be_SeniorSecuredNotesDueMarch2025NonRecourseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=be_PowerPurchaseAgreementCompany3aMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=be_TermLoanDueSeptember2028NonRecourseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=be_PowerPurchaseAgreementCompany3bMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=be_TermLoanDueOctober2020NonRecourseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=be_PowerPurchaseAgreementCompany4Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=be_SeniorSecuredNotesDueMarch2030NonRecourseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=be_PowerPurchaseAgreementCompany5Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=be_TermLoanDueDecember2021NonRecourseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=be_TermLoandueDecember2021YearsOneThroughThreeNonRecourseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=be_TermLoandueDecember2021AfterYearThreeNonRecourseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Outstanding Loans and Security Agreements - Non-recourse Debt Facilities (Additional Information) (Details)	1 Months Ended			6 Months Ended	12 Months Ended
	Jun. 30, 2018 USD ($)	Sep. 30, 2013 USD ($)	Mar. 31, 2013 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Feb. 28, 2017 USD ($)	Jun. 30, 2015 USD ($) lender	Jul. 31, 2014 USD ($)	Dec. 31, 2012 USD ($)
Debt Instrument [Line Items]
Interest rate percentage					8.00%
Unused borrowing capacity	$ 1,504,000			$ 1,504,000	$ 1,784,000
PPA Company II
Debt Instrument [Line Items]
Repayments of debt				$ 59,300,000	$ 53,726,000
PPA Company II \| Senior secured notes \| Senior Secured Notes due March 2025, Non-Recourse
Debt Instrument [Line Items]
Interest rate percentage	5.20%		5.22%	5.20%	5.20%
Total amount of loan proceeds			$ 144,800,000
Repayments of debt			28,800,000
Debt proceeds used for debt service reserves and issuance costs			21,700,000
Debt used to fund remaining system purchases			$ 94,300,000
Debt minimum debt service reserves required	$ 11,200,000			$ 11,200,000	$ 11,300,000
PPA Company IIIa
Debt Instrument [Line Items]
Repayments of debt				$ 3,668,000	$ 3,041,000
PPA Company IIIa \| Term loan \| Term Loan due September 2028, Non-Recourse
Debt Instrument [Line Items]
Interest rate percentage	7.50%			7.50%	7.50%				7.50%
Debt minimum debt service reserves required	$ 3,700,000			$ 3,700,000	$ 3,700,000
Debt face amount									$ 46,800,000
PPA Company IIIb
Debt Instrument [Line Items]
Repayments of debt				3,523,000	3,077,000
PPA Company IIIb \| Term loan \| Term Loan due October 2020, Non-Recourse
Debt Instrument [Line Items]
Debt minimum debt service reserves required	$ 1,700,000			1,700,000	1,700,000
Debt face amount		$ 32,500,000
PPA Company IIIb \| Term loan \| Term Loan due October 2020, Non-Recourse \| LIBOR
Debt Instrument [Line Items]
LIBOR margin (as a percentage)		5.20%
PPA Company IV
Debt Instrument [Line Items]
Repayments of debt				$ 14,582,000	$ 13,697,000
PPA Company IV \| Senior secured notes \| Senior Secured Notes due March 2030, Non-Recourse
Debt Instrument [Line Items]
Interest rate percentage	6.10%			6.10%	6.10%			6.07%
Debt minimum debt service reserves required	$ 7,200,000			$ 7,200,000	$ 7,000,000
Debt face amount								$ 99,000,000
PPA Company V
Debt Instrument [Line Items]
Repayments of debt				4,274,000	2,834,000
PPA Company V \| Term loan \| Term Loan due December 2021, Non-Recourse
Debt Instrument [Line Items]
Debt face amount							$ 131,200,000
Number of lenders \| lender							5
Commitment fee percentage	0.50%
PPA Company V \| Term loan \| Term Loan due December 2021, Years One Through Three, Non-Recourse \| LIBOR
Debt Instrument [Line Items]
LIBOR margin (as a percentage)	2.25%
PPA Company V \| Term loan \| Term Loan due December 2021, After Year Three, Non-Recourse \| LIBOR
Debt Instrument [Line Items]
LIBOR margin (as a percentage)	2.50%
Letters of Credit
Debt Instrument [Line Items]
Unused borrowing capacity	$ 1,504,000			1,504,000	1,784,000
Letters of Credit \| PPA Company V
Debt Instrument [Line Items]
Maximum borrowing capacity						$ 6,200,000	$ 6,400,000
Amount outstanding	4,600,000			4,600,000	4,400,000
Unused borrowing capacity	$ 1,504,000			$ 1,504,000	$ 1,784,000