Spire Global, Inc. Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Additional Information (Detail) $ in Millions		7 Months Ended
	Sep. 14, 2020 USD ($)	Dec. 31, 2020 USD ($)
Initial Measurement [Member] \| Volatility Assumption [Member]
Risk Neutral Probability Rate	18.00
Monte Carlo Simulation Model [Member] \| Initial Measurement [Member]
Period of expiration of warrants after the completion of the initial business combination		5 years
Expected term of warrants		1 year
Warrant exercisable days after the completion of business combination		30 days
Warrant exercisable period from the initial public offering date		12 months
US Treasury (UST) Interest Rate [Member] \| Monte Carlo Simulation Model [Member] \| Initial Measurement [Member]
Description of risk free interest rate assumption based on treasury rate		risk-free interest rate assumption was based on the five-year U.S. Treasury rate
Private Placement [Member]
Aggregate value of liabilities at fair value		$ 8.6
Private Placement [Member] \| Initial Measurement [Member] \| Volatility Assumption [Member]
Aggregate value of liabilities at fair value	$ 5.9
Public Warrants [Member]
Aggregate value of liabilities at fair value		$ 14.7
Public Warrants [Member] \| Initial Measurement [Member] \| Volatility Assumption [Member]
Aggregate value of liabilities at fair value	$ 10.2