XML 72 R63.htm IDEA: XBRL DOCUMENT
v3.23.2

STOCK-BASED COMPENSATION - Summary of option activity (Details) - $ / shares | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2023 | Jun. 30, 2023 | Dec. 31, 2022
Number of Stock Options |  |  |
Outstanding (in shares) |  | 2,591,063 |
Granted (in shares) | 0 | 0 |
Forfeited (in shares) |  | (91,200) |
Outstanding (in shares) | 2,499,863 | 2,499,863 | 2,591,063
Exercisable, end of period (in shares) | 0 | 0 |
Weighted Average Grant Date Fair Value |  |  |
Outstanding (in dollars per share) |  | $ 4.12 |
Forfeited (in dollars per share) |  | 4.25 |
Outstanding (in dollars per share) | $ 4.12 | 4.12 | $ 4.12
Weighted Average Exercise Price |  |  |
Outstanding (in dollars per share) |  | 11.65 |
Forfeited (in dollars per share) |  | 11.69 |
Outstanding (in dollars per share) | $ 11.65 | $ 11.65 | $ 11.65
Weighted Average Remaining Contractual Life (years) |  |  |
Outstanding (in years) |  | 9 years 3 months 18 days | 9 years 9 months 18 days
Forfeited (in years) |  | 9 years 3 months 18 days |

X
- Definition Share Based Compensation Arrangement by Share-Based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Remaining Contractual Life + References No definition available. + Details
Name: | blue_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageRemainingContractualLife
Namespace Prefix: | blue_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Outstanding, Weighted Average Grant Date Fair Value + References No definition available. + Details
Name: | blue_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageGrantDateFairValue
Namespace Prefix: | blue_
Data Type: | dtr-types1:perShareItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(03) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Gross number of share options (or share units) granted during the period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(ii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(ii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(03) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average grant-date fair value of non-vested options forfeited. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Subparagraph (e)(1) -Name Accounting Standards Codification -Paragraph 2 -Section 50 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration