Unaudited Quarterly Financial Information (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Income (Loss) [Abstract]
Revenue	$ 52,918		$ 41,593		$ 46,074		$ 46,001		$ 38,979		$ 51,197		$ 55,610		$ 47,748		$ 186,586	$ 193,534	$ 159,258
Gross profit	18,500		15,470		16,600		17,870		14,374		21,113		21,576		18,230		68,440	75,293	65,052
Net income (loss)	(2,118)	[1]	(3,292)	[2]	(1,181)	[3]	319	[4]	(2,814)	[5]	6,027	[6]	3,405	[7]	(278)	[2]	(6,272)	6,340	7,174
Basic and diluted net income (loss) per share	$ (0.07)		$ (0.11)		$ (0.04)		$ 0.01		$ (0.10)		$ 0.21		$ 0.12		$ (0.01)
Stock-based compensation expense	1,035		1,011		1,166		755		1,358		719		946		957		3,967	3,980	3,088
Withholding tax on undistributed earnings of foreign subsidiary	$ (1,590)								$ 0								$ (1,590)	$ 0

[1] Includes a non-cash deferred tax expense of $1.6 million in connection with the probable repatriation of a portion of the unremitted earnings of a foreign subsidiary and a non-cash expense for stock-based compensation of $1.0 million.

[2] Includes a non-cash expense for stock-based compensation of $1.0 million.

[3] Includes a non-cash expense for stock-based compensation of $1.2 million.

[4] Includes a non-cash expense for stock-based compensation of $755,000.

[5] Includes a non-cash expense for stock-based compensation of $1.4 million.

[6] Includes a non-cash expense for stock-based compensation of $719,000.

[7] Includes a non-cash expense for stock-based compensation of $946,000