Supplemental Executive Retirement Plans - Plan details and change in benefit obligation (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) payment	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Retirement Benefits [Abstract]
Number of annual payments | payment	15
Change in Benefit Obligation
Benefit obligation at the beginning of the period	$ 17,935	$ 19,746
Service cost	116	123
Interest cost	99	87
Payments	(1,877)	(1,877)
Benefit obligation at the end of the period	16,273	$ 18,079
Amounts Recognized in the Condensed Consolidated Balance Sheets:
Current accrued expenses and other current liabilities	1,913		$ 1,913
Non-current other liabilities	14,360		16,022
Total accrued liabilities	$ 16,273		$ 17,935