Summary of Significant Accounting Policies - Revenue Recognition - Condensed Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Summary of Significant Accounting Policies
Accumulated deficit	$ (133,993)	$ (117,539)
Current assets:
Accounts receivable, net	7,522	4,041
Inventory	9,097	9,837
Total current assets	40,686	27,418
Total assets	45,045	31,437
Current liabilities:
Deferred income on shipments to distributors		1,720
Total current liabilities	13,615	12,375
Total liabilities	20,124	20,553
Stockholders’ equity:
Accumulated deficit	(133,993)	(117,539)
Total liabilities and stockholders' equity	45,045	31,437
ASU 2014-09 | Balances without the adoption of Topic 606
Summary of Significant Accounting Policies
Accumulated deficit	(138,031)
Current assets:
Accounts receivable, net	6,311
Inventory	9,287
Total current assets	39,665
Total assets	44,024
Current liabilities:
Deferred income on shipments to distributors	3,017
Total current liabilities	16,632
Total liabilities	23,141
Stockholders’ equity:
Accumulated deficit	(138,031)
Total liabilities and stockholders' equity	44,024
ASU 2014-09 | Adjustments
Summary of Significant Accounting Policies
Accumulated deficit	(4,038)	1,300
Current assets:
Accounts receivable, net	(1,211)
Inventory	190
Total current assets	(1,021)
Total assets	(1,021)
Current liabilities:
Deferred income on shipments to distributors	3,017
Total current liabilities	3,017
Total liabilities	3,017
Stockholders’ equity:
Accumulated deficit	(4,038)	$ 1,300
Total liabilities and stockholders' equity	$ (1,021)