Employee Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
The Plan
Employee Benefit Plans:
Number of common stock shares reserved for issuance (in shares)	650,000
Employer match of employee contributions of first 3% of eligible compensation (as a percent)	100.00%
Percentage of eligible compensation, matched 100% by employer (as a percent)	3.00%
Employer match of employee contributions of next 2% of eligible compensation (as a percent)	50.00%
Percentage of eligible compensation, matched 50% by employer (as a percent)	2.00%
Employer contribution	$ 3,455	$ 3,346	$ 3,422
Deferred Compensation Plans
Employee Benefit Plans:
Employer contribution	$ 695	$ 814	$ 813