Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2018			11,417,863
Beginning balance at Dec. 31, 2018	$ 256,825	$ (264)	$ 114	$ 83,712	$ 180,356	$ (264)	$ (7,357)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	32,461				32,461
Other comprehensive income (loss), net of tax	(911)						(911)
Employee stock purchase plan (in shares)			26,521
Employee stock purchase plan	1,118			1,118
Stock options exercised (in shares)			80,693
Stock options exercised	2,015		$ 1	2,014
Stock repurchased related to the exercise of stock options and stock awards vested (in shares)			(123,192)
Stock repurchased related to the exercise of stock options and stock awards vested	(5,605)		$ (1)	(5,604)
Stock awards vested (in shares)			170,783
Stock awards vested	0		$ 2	(2)
Stock-based compensation	7,161			7,161
Ending balance (in shares) at Dec. 31, 2019			11,572,668
Ending balance at Dec. 31, 2019	292,800		$ 116	88,399	212,553		(8,268)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	29,174				29,174
Other comprehensive income (loss), net of tax	(1,332)						(1,332)
Employee stock purchase plan (in shares)			57,285
Employee stock purchase plan	2,194		$ 1	2,193
Stock options exercised (in shares)			54,063
Stock options exercised	1,564		$ 1	1,563
Stock repurchased related to the exercise of stock options and stock awards vested (in shares)			(95,411)
Stock repurchased related to the exercise of stock options and stock awards vested	(4,365)		$ (2)	(4,363)
Stock awards vested (in shares)			139,607
Stock awards vested	0		$ 1	(1)
Stock-based compensation	9,299			9,299
Ending balance (in shares) at Dec. 31, 2020			11,728,212
Ending balance at Dec. 31, 2020	329,334		$ 117	97,090	241,727		(9,600)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	135,536				135,536
Other comprehensive income (loss), net of tax	2,567						2,567
Employee stock purchase plan (in shares)			56,524
Employee stock purchase plan	$ 2,904		$ 1	2,903
Stock options exercised (in shares)	48,769		48,769
Stock options exercised	$ 1,733		$ 1	1,732
Stock repurchased related to the exercise of stock options and stock awards vested (in shares)			(155,653)
Stock repurchased related to the exercise of stock options and stock awards vested	(8,684)		$ (2)	(8,682)
Stock awards vested (in shares)			247,235
Stock awards vested	0		$ 2	(2)
Stock-based compensation	11,212			11,212
Ending balance (in shares) at Dec. 31, 2021			11,925,087
Ending balance at Dec. 31, 2021	$ 474,602		$ 119	$ 104,253	$ 377,263		$ (7,033)