Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Products									$ 256,263	$ 258,968	$ 304,973
Services									6,569	10,998	14,879
Total revenues	$ 70,604	$ 64,337	$ 64,079	$ 63,812	$ 63,863	$ 74,048	$ 71,949	$ 60,106	262,832	269,966	319,852
Cost of Revenue:
Products									162,487	164,837	179,258
Services									7,768	7,196	8,257
Depreciation									1,899	1,627	1,573
Total cost of revenue									$ 172,154	$ 173,660	$ 189,088