CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2012	$ 381,577	$ 172,341	$ 210,418	$ (1,182)
Beginning balance (in shares) at Dec. 31, 2012		42,489
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16,570		16,570
Other comprehensive income	2,125			2,125
Excess tax benefits from stock-based compensation	259	$ 259
Stock-based compensation expense	1,467	1,467
Options exercised	3,733	$ 3,733
Options exercised (in shares)		413
Issuance of common stock under Employee Stock Purchase Plans	448	$ 448
Issuance of common stock under Employee Stock Purchase Plans (in shares)		37
Shares surrendered in exchange for payment of payroll tax liabilities	(21)	$ (21)
Shares surrendered in exchange for payment of payroll tax liabilities (in shares)		(48)
Shares surrendered in exchange for the exercise of stock options	(452)	$ (452)
Shares surrendered in exchange for the exercise of stock options (in shares)		(45)
Ending balance at Dec. 31, 2013	405,706	$ 177,775	226,988	943
Ending balance (in shares) at Dec. 31, 2013		42,846
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	22,974		22,974
Other comprehensive income	(3,355)			(3,355)
Excess tax benefits from stock-based compensation	576	$ 576
Stock-based compensation expense	1,460	1,460
Options exercised	9,638	$ 9,638
Options exercised (in shares)		878
Issuance of common stock under Employee Stock Purchase Plans	450	$ 450
Issuance of common stock under Employee Stock Purchase Plans (in shares)		33
Shares surrendered in exchange for payment of payroll tax liabilities	(249)	$ (249)
Shares surrendered in exchange for payment of payroll tax liabilities (in shares)		(16)
Shares surrendered in exchange for the exercise of stock options	(1,941)	$ (1,941)
Shares surrendered in exchange for the exercise of stock options (in shares)		(127)
Ending balance at Dec. 31, 2014	$ 435,259	$ 187,709	249,962	(2,412)
Ending balance (in shares) at Dec. 31, 2014	43,614	43,614
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 23,802		23,802
Other comprehensive income	(3,075)			(3,075)
Excess tax benefits from stock-based compensation	2,124	$ 2,124
Stock-based compensation expense	2,243	2,243
Options exercised	$ 10,029	$ 10,029
Options exercised (in shares)	858	858
Issuance of common stock under Employee Stock Purchase Plans	$ 441	$ 441
Issuance of common stock under Employee Stock Purchase Plans (in shares)		23
Shares surrendered in exchange for payment of payroll tax liabilities	(918)	$ (918)
Shares surrendered in exchange for payment of payroll tax liabilities (in shares)		(43)
Shares surrendered in exchange for the exercise of stock options	(3,802)	$ (3,802)
Shares surrendered in exchange for the exercise of stock options (in shares)		(185)
Ending balance at Dec. 31, 2015	$ 466,103	$ 197,826	$ 273,764	$ (5,487)
Ending balance (in shares) at Dec. 31, 2015	44,267	44,267