Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details)

v3.22.1
Summary of Significant Accounting Policies (Details)
$ in Thousands
Dec. 31, 2021
USD ($)
Net Investment Income [Line Items]  
Marketable investments $ 112,523
Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 55,252
Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments 57,271
Corporate Bond Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 47,335
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 31,099
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments 16,236
US Treasury Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 24,153
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 24,153
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 7,361
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 7,361
U S Agency And Government Sponsored Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 14,588
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 14,588
US Treasury Notes Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 11,682
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 11,682
Asset-backed Securities [Member]  
Net Investment Income [Line Items]  
Marketable investments 6,406
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 6,406
Commercial Paper [Member]  
Net Investment Income [Line Items]  
Marketable investments 998
Commercial Paper [Member] | Fair Value, Inputs, Level 1 [Member]  
Net Investment Income [Line Items]  
Marketable investments 0
Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member]  
Net Investment Income [Line Items]  
Marketable investments $ 998