Equity Incentive Plan - Option grants to employees and non-employees (Details) - Options - BFLY Operations Inc	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate, minimum	0.40%	2.30%
Risk free interest rate, maximum	1.70%	2.50%
Expected dividend yield	0.00%	0.00%
Expected volatility	50.00%	50.00%
Employees \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	5 years 10 months 24 days	6 years
Employees \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	6 years 3 months 18 days	6 years 1 month 6 days
Non-employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate, minimum	0.40%	1.50%
Risk free interest rate, maximum	1.70%	2.70%
Expected dividend yield	0.00%	0.00%
Expected volatility	50.00%	50.00%
Non-employees \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	1 year 1 month 6 days	8 years 1 month 6 days
Non-employees \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	6 years 1 month 6 days	10 years

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

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- Definition

The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

+ Details

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- Definition

The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

No definition available.

+ Details

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- 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.

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- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 718
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-Paragraph 2
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-Name Accounting Standards Codification
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-Section S99
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