Investments in held-to-maturity debt securities (Details 2) $ in Thousands	Mar. 31, 2022 USD ($)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value
Fair value, Less than 12 months	$ 2,405	[1]
Fair value, 12 months or more	0	[1]
Fair value	2,405	[1]
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss
Gross unrealized losses, Less than 12 months	(9)
Gross unrealized losses, 12 months or more	0
Gross unrealized losses	(9)
U.S. government
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value
Fair value, Less than 12 months	298	[1]
Fair value, 12 months or more	0	[1]
Fair value	298	[1]
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss
Gross unrealized losses, Less than 12 months	(2)
Gross unrealized losses, 12 months or more	0
Gross unrealized losses	(2)
Corporate and other taxable bonds
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value
Fair value, Less than 12 months	1,673	[1]
Fair value, 12 months or more	0	[1]
Fair value	1,673	[1]
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss
Gross unrealized losses, Less than 12 months	(6)
Gross unrealized losses, 12 months or more	0
Gross unrealized losses	(6)
Extended fixed funds
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value
Fair value, Less than 12 months	434	[1]
Fair value, 12 months or more	0	[1]
Fair value	434	[1]
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss
Gross unrealized losses, Less than 12 months	(1)
Gross unrealized losses, 12 months or more	0
Gross unrealized losses	$ (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.