Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies (Details)

v3.22.1
Summary of Significant Accounting Policies (Details)
$ in Thousands
Mar. 31, 2022
USD ($)
Net Investment Income [Line Items]  
Marketable investments $ 101,301
Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 53,277
Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments 48,024
Corporate Bond Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 44,232
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 29,883
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments 14,349
US Treasury Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 23,394
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 23,394
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments 0
Collateralized Mortgage-Backed Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 6,653
Collateralized Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 0
Collateralized Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments 6,653
U S Agency And Government Sponsored Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 13,239
U S Agency And Government Sponsored Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 0
U S Agency And Government Sponsored Securities [Member] | Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments 13,239
US Treasury Notes Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 11,219
US Treasury Notes Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 0
US Treasury Notes Securities [Member] | Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments 11,219
Asset-Backed Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 2,564
Asset-Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 0
Asset-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments $ 2,564