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

Summary of Significant Accounting Policies - Financial instruments at fair value on a recurring basis (Details)

v3.21.1
Summary of Significant Accounting Policies - Financial instruments at fair value on a recurring basis (Details) - Blade Urban Air Mobility [Member] - Commission Liability [Member ] - USD ($)
$ in Thousands
Sep. 30, 2019
Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of liability $ 73 $ 527
Measured on a recurring basis | Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of liability $ 73