Unaudited Quarterly Financial Information (Details) - USD ($)	3 Months Ended																12 Months Ended
	Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Operating Income (Loss) [Abstract]
Revenue	$ 30,763,000		$ 35,816,000		$ 37,103,000		$ 26,686,000		$ 26,400,000		$ 25,506,000		$ 34,135,000		$ 35,203,000		$ 130,368,000	[1]	$ 121,244,000	[1]	$ 167,372,000	[1]
Gross profit	7,381,000		7,396,000		7,827,000		6,191,000		5,708,000		7,628,000		9,981,000		9,653,000		28,795,000		32,970,000		50,962,000
Net loss	$ (8,752,000)	[2]	$ (13,860,000)	[3]	$ (10,118,000)	[4]	$ (10,399,000)	[5]	$ (12,169,000)	[6]	$ (6,855,000)	[7]	$ 2,167,000	[8]	$ (6,848,000)	[9]	$ (43,129,000)		$ (23,705,000)		$ (22,333,000)
Basic and diluted net (loss) income per share	$ (0.24)		$ (0.37)		$ (0.28)		$ (0.32)		$ (0.38)		$ (0.21)		$ 0.07		$ (0.22)		$ (1.22)		$ (0.74)		$ (0.73)
Stock-based compensation expense	$ 2,500,000		$ 2,800,000		$ 2,300,000		$ 1,500,000		$ 1,600,000		$ 1,100,000		$ 1,500,000		$ 1,200,000		$ 9,037,000		$ 5,364,000		$ 3,946,000
Acquisition related costs					$ 1,800,000
Gain on sale of product line													6,700,000				0		6,657,000		0
Release of tax liability													$ 1,500,000				0		(1,518,000)		0
Impairment of assets									1,200,000								240,000		1,389,000		0
Foreign taxes on unremitted earnings									$ 1,200,000								0		1,204,000		2,085,000
Restructuring and exit costs			1,300,000				$ 1,000,000										$ 2,282,000		$ 297,000		$ 2,512,000
SEC and FCPA legal and settlement costs			$ 3,000,000

[1] Location is determined by shipment destination.

[2] Includes non-cash expense for stock-based compensation of $2.5 million.

[3] Includes restructuring and exit costs of $1.3 million, SEC and FCPA legal and settlement costs of $3.0 million and non-cash expense for stock-based compensation of $2.8 million.

[4] Includes acquisition related expense of $1.8 million and non-cash expense for stock-based compensation of $2.3 million.

[5] Includes restructuring and exit costs of $1.0 million and non-cash expense for stock-based compensation of $1.5 million.

[6] Includes impairment of assets of $1.2 million, non-cash deferred tax expense of $1.2 million in connection with the probable repatriation of a portion of the unremitted earnings of a foreign subsidiary and non-cash expense for stock-based compensation of $1.6 million.

[7] Includes non-cash expense for stock-based compensation of $1.1 million.

[8] Includes gain on sale of product line of $6.7 million, release of tax liability of $1.5 million and non-cash expense for stock-based compensation of $1.5 million.

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