Summary of Significant Accounting Policies - Reconciliation of shares used to determine net income per share (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Summary of Significant Accounting Policies
Net income	$ 19,189	$ 39,810	$ 34,720	$ 69,365
Weighted average number of shares - basic	45,339,570	44,960,464	45,319,155	44,870,642
Shares underlying options	1,957,849	2,191,793	1,986,041	2,103,799
Weighted average number of shares outstanding - diluted	47,297,419	47,152,257	47,305,196	46,974,441