Investments and fair value measurements (Tables)
 3 Months Ended
Mar. 31, 2022
Investments, All Other Investments [Abstract]  
Summary of Held-to-Maturity Debt Securities
The cost basis, fair values and gross unrealized gains and losses of our held-to-maturity debt securities are as follows:
March 31, 2022December 31, 2021
Amortized CostUnrealized GainsUnrealized LossesFair ValueAmortized CostUnrealized GainsUnrealized LossesFair Value
Corporate debt securities(1)
$55,727 $42 $(906)$54,863 $62,078 $459 $(207)$62,330 
U.S. Treasury securities6,834 — (98)6,736 4,849 — (16)4,833 
Certificates of deposit237 — — 237 237 — — 237 
Total$62,798 $42 $(1,004)$61,836 $67,164 $459 $(223)$67,400 
_______________
(1)Includes both U.S. and foreign corporate debt securities.
Summary of Investments by Maturity Date
The following table presents certain information regarding contractual maturities of our held-to-maturity debt securities:
MaturityMarch 31, 2022
Amortized Cost
% of
Total
Fair Value
% of
Total
One year or less
$30,051 48 %$29,973 48 %
After one year through five years
$32,747 52 %$31,863 52 %
Total$62,798 100 %$61,836 100 %
Schedule of Unrealized Loss on Held-to-Maturity Debt Securities
Net unrealized losses on held-to-maturity debt securities and the fair value of the related securities, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position are as follows:
March 31, 2022December 31, 2021
Corporate debt securitiesU.S. Treasury securitiesCertificate of depositsTotalCorporate debt securitiesU.S. Treasury securitiesCertificate of depositsTotal
Less than 12 months
Fair value
$40,973 $6,571 $— $47,544 $18,309 $4,667 $— $22,976 
Unrealized losses
$(836)$(98)$— $(934)$(192)$(16)$— $(208)
Greater than 12 months
Fair value$1,085 $— $— $1,085 $605 $— $— $605 
Unrealized losses$(70)$— $— $(70)$(15)$— $— $(15)
Total
Fair value$42,058 $6,571 $— $48,629 $18,914 $4,667 $— $23,581 
Unrealized losses$(906)$(98)$— $(1,004)$(207)$(16)$— $(223)
Summary of Held to Maturity Debt Securities Allowance for Credit Loss The calculated
allowance is recorded as an offset to held-to-maturity debt securities in the condensed consolidated balance sheets and in the investment, dividend and other income line on the condensed consolidated statements of operations.
Rollforward of Credit Loss Allowance for Held-to-Maturity Debt Securities
Beginning balance, January 1, 2022
$399 
Current-period provision (reduction) for expected credit losses
(17)
Write-off charged against the allowance, if any
— 
Recoveries of amounts previously written off, if any
— 
Ending balance of the allowance for credit losses, March 31, 2022
$382 
Summary of Available-for-Sale Debt Securities
The following table reflects the composition of net realized gains or losses for the sales of the available-for-sale securities:
Three months ended March 31,
20222021
Realized gains (losses):
Available-for-sale debt securities:
Gains
$— $768 
Losses
— (90)
Net
$— $678 
Schedule of Cost and Estimated Fair Value of Mortgage Loans and Accrued Interest Receivable
The cost and estimated fair value of mortgage loans are as follows:
March 31, 2022December 31, 2021
CostEstimated Fair ValueCostEstimated Fair Value
Mortgage loans
$1,141 $1,141 $2,022 $2,022 
Total
$1,141 $1,141 $2,022 $2,022 
Accrued interest receivable from investments is included in receivables, net in the condensed consolidated balance sheets. The following table reflects the composition of accrued interest receivable for investments:
March 31, 2022December 31, 2021
Corporate debt securities
$409 $874 
U.S. Treasury securities
20 12 
Accrued interest receivable on investment securities
$429 $886 
Mortgage loans
8 13 
Accrued interest receivable on investments
$437 $899 
Schedule of Investment Income
Investment income from securities consists of the following:
Three months ended March 31,
20222021
Available-for-sale debt securities
$— $773 
Held-to-maturity debt securities
389 394 
Equity investments
— (89)
Mortgage loans
22 46 
Other
44 60 
Total
$455 $1,184 
Summary of Company's Assets Measured at Fair Value
The following table summarizes the Company’s investments measured at fair value:
Assets
Corporate debt securitiesU.S. Treasury securitiesMortgage loansCertificate of depositsTotal
March 31, 2022
Level 1
$— $6,736 $— $— $6,736 
Level 2
54,863 — — 237 55,100 
Level 3
— — 1,141 — 1,141 
Total
$54,863 $6,736 $1,141 $237 $62,977 
December 31, 2021
Level 1
$— $4,833 $— $— $4,833 
Level 2
62,330 — — 237 62,567 
Level 3
— — 2,022 — 2,022 
Total
$62,330 $4,833 $2,022 $237 $69,422 
Summary of Company's Liabilities Measured at Fair Value
The Company’s liabilities in the following table are recorded at fair value on the accompanying condensed consolidated balance sheets. The following table summarizes the Company’s liabilities measured at fair value:
Liabilities
Public WarrantsPrivate Placement WarrantsSponsor Covered SharesTotal
March 31, 2022
Level 1
$4,025 $— $— $4,025 
Level 2
— 2,042 — 2,042 
Level 3
— — 1,916 1,916 
Total
$4,025 $2,042 $1,916 $7,983 
December 31, 2021
Level 1
$10,925 $— $— $10,925 
Level 2
— 5,542 — 5,542 
Level 3
— — 5,415 5,415 
Total
$10,925 $5,542 $5,415 $21,882 
Summary of the Fair Values of the Sponsor Earnout Shares Using a Monte Carlo Simulation Valuation Model
The fair value of the Sponsor Covered Shares was determined using a Monte Carlo simulation valuation model using a distribution of potential stock price outcomes on a daily basis over the 10-year vesting period. The unobservable significant inputs to the valuation model were as follows:
 March 31,
2022
Current stock price$2.17 
Expected volatility60.0 %
Risk-free interest rate2.32 %
Expected term9.3 years
Expected dividend yield— %
Annual change in control probability2.0 %
Summary of Changes for Level 3 Items Measured at Fair Value
The changes for Level 3 items measured at fair value on a recurring basis using significant unobservable inputs are as follows:
Sponsor Covered Shares
Fair value as of December 31, 2021
$5,415 
Change in fair value of Sponsor Covered Shares(3,499)
Fair value as of March 31, 2022
$1,916