Consolidated statements of changes in stockholders' equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	(Accumulated Deficit) Retained Earnings
Number of shares outstanding, beginning balance (in shares) at Dec. 31, 2016		15,891,000
Stockholders' equity attributable to parent, beginning balance at Dec. 31, 2016	$ 151,226	$ 16	$ 213,872	$ (37,003)	$ (25,659)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	(15,429)		(15,429)
Issuance of common stock upon exercise of stock option grants (in shares)		198,000
Proceeds from Stock Options Exercised	4,338
Issuance of common stock upon exercise of stock option grants	4,338		4,338
Payment, Tax Withholding, Share-based Payment Arrangement	0
Payments for Repurchase of Common Stock	43,792
Common stock repurchases	(43,792)			(43,792)
Net income	51,943				51,943
Number of shares outstanding, ending balance (in shares) at Dec. 31, 2017		16,089,000
Stockholders' equity attributable to parent, ending balance at Dec. 31, 2017	179,144	$ 16	233,639	(80,795)	26,284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	$ (19,082)		(19,082)
Issuance of common stock upon exercise of stock option grants (in shares)	502,322	415,000
Proceeds from Stock Options Exercised	$ 8,615
Issuance of common stock upon exercise of stock option grants	8,615	$ 1	8,614
Payment, Tax Withholding, Share-based Payment Arrangement	0
Payments for Repurchase of Common Stock	73,105
Payments for employee net option exercises	(4,877)		(4,877)
Common stock repurchases	(73,105)			(73,105)
Net income	31,903				31,903
Number of shares outstanding, ending balance (in shares) at Dec. 31, 2018		16,504,000
Stockholders' equity attributable to parent, ending balance at Dec. 31, 2018	160,762	$ 17	256,458	(153,900)	58,187
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	$ 21,998
Issuance of common stock upon exercise of stock option grants (in shares)	23,032	34,000
Proceeds from Stock Options Exercised	$ 260
Issuance of common stock upon exercise of stock option grants	260
Payment, Tax Withholding, Share-based Payment Arrangement	198
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(198)
Payments for Repurchase of Common Stock	17,961
Common stock repurchases	(17,961)
Net income	14,313				14,313
Number of shares outstanding, ending balance (in shares) at Dec. 31, 2019		16,538,000
Stockholders' equity attributable to parent, ending balance at Dec. 31, 2019	$ 179,174	$ 17	$ 278,518	$ (171,861)	$ 72,500