General form of registration statement for all companies including face-amount certificate companies

Summary of Significant Accounting Policies - Concentrations (Details)

v3.21.1
Summary of Significant Accounting Policies - Concentrations (Details) - Blade Urban Air Mobility [Member]
3 Months Ended 6 Months Ended 12 Months Ended
Mar. 31, 2021
item
Mar. 31, 2020
item
Mar. 31, 2021
item
Mar. 31, 2020
item
Sep. 30, 2020
item
customer
Sep. 30, 2019
item
customer
Concentration Risk [Line Items]            
Risk concentration percentage 10.00% 12.00% 10.00% 15.00% 10.00% 10.00%
Number of customers | customer         0 0
Number of vendor 0 1 0 1   2
Trade receivables            
Concentration Risk [Line Items]            
Risk concentration percentage           75.00%
Purchases from vendors            
Concentration Risk [Line Items]            
Risk concentration percentage         12.00%  
Number of customers         3  
Number of vendor 4       1 3
Customer one            
Concentration Risk [Line Items]            
Risk concentration percentage           30.00%
Customer one | Trade receivables            
Concentration Risk [Line Items]            
Risk concentration percentage 28.00%       36.00%  
Customer one | Purchases from vendors            
Concentration Risk [Line Items]            
Risk concentration percentage           15.00%
Customer two            
Concentration Risk [Line Items]            
Risk concentration percentage           11.00%
Customer two | Trade receivables            
Concentration Risk [Line Items]            
Risk concentration percentage 23.00%       29.00%  
Customer two | Purchases from vendors            
Concentration Risk [Line Items]            
Risk concentration percentage           15.00%
Customer three | Trade receivables            
Concentration Risk [Line Items]            
Risk concentration percentage 17.00%       10.00%  
Customer three | Purchases from vendors            
Concentration Risk [Line Items]            
Risk concentration percentage           11.00%
Vendor concentration            
Concentration Risk [Line Items]            
Risk concentration percentage     62.00% 26.00% 26.00%  
Number of vendor     1 1 1