CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Total
Beginning balance at Dec. 31, 2018	$ 571,383	$ 363,425	$ (2,033)	$ 932,775
Beginning balance (in shares) at Dec. 31, 2018	54,893
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		6,195		6,195
Cumulative effect adjustment upon adoption of ASU | ASU 2016-02		93		93
Other comprehensive loss			(2,515)	(2,515)
Stock-based compensation expense	$ 1,766			1,766
Options exercised	$ 1,365			1,365
Options exercised (in shares)	95
Issuance of common stock under Employee Stock Purchase Plan	$ 432			432
Issuance of common stock under Employee Stock Purchase Plans (in shares)	7
Ending balance at Mar. 31, 2019	$ 574,946	369,713	(4,548)	940,111
Ending balance (in shares) at Mar. 31, 2019	54,995
Beginning balance at Dec. 31, 2019	$ 587,017	368,221	(5,294)	$ 949,944
Beginning balance (in shares) at Dec. 31, 2019	55,213			55,213
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(3,154)		$ (3,154)
Cumulative effect adjustment upon adoption of ASU | ASU 2016-13		(575)		(575)
Other comprehensive loss			(9,465)	(9,465)
Stock-based compensation expense	$ 2,641			2,641
Options exercised	$ 2,369			2,369
Options exercised (in shares)	174
Issuance of common stock under Employee Stock Purchase Plan	$ 371			371
Issuance of common stock under Employee Stock Purchase Plans (in shares)	13
Shares surrendered in exchange for payment of payroll tax liabilities	$ (866)			(866)
Shares surrendered in exchange for payment of payroll tax liabilities (in shares)	(23)
Shares surrendered in exchange for exercise of stock options	$ (1,467)			(1,467)
Shares surrendered in exchange for exercise of stock options (in shares)	(39)
Ending balance at Mar. 31, 2020	$ 590,065	$ 364,492	$ (14,759)	$ 939,798
Ending balance (in shares) at Mar. 31, 2020	55,338			55,338