Investments in held-to-maturity debt securities (Details) $ in Thousands	Mar. 31, 2022 USD ($)
Investments in held-to-maturity debt securities
Amortized cost	$ 2,414
Unrealized Gains	0
Unrealized Losses	(9)
Fair value	2,405	[1]
U.S. government
Investments in held-to-maturity debt securities
Amortized cost	300
Unrealized Gains	0
Unrealized Losses	(2)
Fair value	298	[1]
Corporate and other taxable bonds
Investments in held-to-maturity debt securities
Amortized cost	1,679
Unrealized Gains	0
Unrealized Losses	(6)
Fair value	1,673	[1]
Extended fixed funds
Investments in held-to-maturity debt securities
Amortized cost	435
Unrealized Gains	0
Unrealized Losses	(1)
Fair value	$ 434	[1]

[1] The fair value of the Company's held-to-maturity debt securities are determined based upon inputs, other than the quoted prices in active markets, that are observable either directly or indirectly, and are classified as level 2 fair value measurements.