Preferred stock (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Equity [Abstract]
Series B convertible preferred stock, $10 par value, liquidation value of $100, authorized 100 shares, issued and outstanding one share	$ 1,000	$ 1,000
Preferred Stock, Par or Stated Value Per Share	$ 10	$ 10
Preferred Stock, Liquidation Preference, Value	$ 100	$ 100
Preferred Stock, Shares Authorized	100	100
Preferred Stock, Shares Outstanding	1	1
Preferred Stock, Shares Issued	1	1