Employee Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee benefits
Matching contribution equals to employees deferrals	100.00%
Employer contributions to contribution plans	$ 629,000	$ 464,000	$ 294,000
Maximum
Employee benefits
Matching contribution as a percentage of employees compensation	3.00%