Condensed Consolidated Statements of Changes in Stockholders' Deficit Statement - USD ($) shares in Thousands, $ in Thousands		Total	Accumulated Deficit	Other Comprehensive Loss	Additional Paid-in Capital	Common Stock
Shares, Outstanding						25,421
Stockholders' Equity Attributable to Parent		$ 40,109	$ (313,102)	$ (99)	$ 353,308	$ 2
Adjustments to Additional Paid in Capital, Warrant Issued		749			749
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period						139
Stock Issued During Period, Value, Stock Options Exercised		412			411
Stock Issued During Period, Shares, Employee Stock Purchase Plans						136
Stock Issued During Period, Value, Employee Stock Purchase Plan		767			767
APIC, Share-based Payment Arrangement, Increase for Cost Recognition		2,945			2,945
Net loss		(19,202)	(19,202)
Other Comprehensive Income (Loss), Net of Tax		(13)		(13)
Net loss		(56,290)
Shares, Outstanding						25,696
Stockholders' Equity Attributable to Parent		25,012	(333,059)	(112)	358,180	$ 3
Cumulative Effect of New Accounting Principle in Period of Adoption	[1]	(755)	(755)
Adjustments to Additional Paid in Capital, Warrant Issued		674			674
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period						89
Stock Issued During Period, Value, Stock Options Exercised		583			583	$ 0
APIC, Share-based Payment Arrangement, Increase for Cost Recognition		2,903			2,903
Net loss		(20,601)	(20,601)
Other Comprehensive Income (Loss), Net of Tax		46		46
Shares, Outstanding						25,785
Stockholders' Equity Attributable to Parent		8,617	(353,660)	(66)	362,340	$ 3
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs					3,700
Stock Issued During Period, Shares, New Issues						4,600
Stock Issued During Period, Value, New Issues		53,847			53,847	$ 0
Adjustments to Additional Paid in Capital, Warrant Issued		843			843
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period						163
Stock Issued During Period, Value, Stock Options Exercised		1,733			1,733	$ 0
Stock Issued During Period, Shares, Employee Stock Purchase Plans						121
Stock Issued During Period, Value, Employee Stock Purchase Plan		684			684
Exercise Price Of Common Stock Warrants						100
Stock Issued During Period, Value, Other		0			0
APIC, Share-based Payment Arrangement, Increase for Cost Recognition		2,835			2,835
Net loss		(16,486)	(16,486)
Other Comprehensive Income (Loss), Net of Tax		12		12
Shares, Outstanding						30,769
Stockholders' Equity Attributable to Parent		52,085	(370,146)	(54)	422,282	$ 3
Cumulative Effect of New Accounting Principle in Period of Adoption	[1]	(1)	(1)
Shares, Outstanding						30,913
Stockholders' Equity Attributable to Parent		36,869	(391,256)	(40)	428,162	$ 3
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs					4,700
Stock Issued During Period, Shares, New Issues						3,175
Stock Issued During Period, Value, New Issues		68,273			68,273	$ 0
Adjustments to Additional Paid in Capital, Warrant Issued		698			698
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period						805
Stock Issued During Period, Value, Stock Options Exercised		8,075			8,075
Stock Issued During Period, Shares, Employee Stock Purchase Plans						151
Stock Issued During Period, Value, Employee Stock Purchase Plan		939			939
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures						0
Stock Issued During Period, Value, Restricted Stock Award, Gross		(1,299)			(1,299)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition		2,882			2,882
Net loss		(21,898)	(21,898)
Other Comprehensive Income (Loss), Net of Tax		61		61
Net loss		(64,683)
Shares, Outstanding						35,044
Stockholders' Equity Attributable to Parent		94,600	(413,154)	21	507,730	$ 3
Adjustments to Additional Paid in Capital, Warrant Issued		1,575			1,575
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period						323
Stock Issued During Period, Value, Stock Options Exercised		4,591			4,590	$ 1
APIC, Share-based Payment Arrangement, Increase for Cost Recognition		5,076			5,076
Net loss		(20,037)
Other Comprehensive Income (Loss), Net of Tax		183		183
Shares, Outstanding						35,367
Stockholders' Equity Attributable to Parent		85,988	(433,191)	204	518,971	$ 4
Adjustments to Additional Paid in Capital, Warrant Issued		516			516
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period						317
Stock Issued During Period, Value, Stock Options Exercised		3,234			3,234
Stock Issued During Period, Shares, Employee Stock Purchase Plans						52
Stock Issued During Period, Value, Employee Stock Purchase Plan		1,013			1,013
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures						0
Stock Issued During Period, Value, Restricted Stock Award, Gross		(175)			(175)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition		4,748			4,748
Net loss		(22,748)
Other Comprehensive Income (Loss), Net of Tax		13		13
Shares, Outstanding						35,736
Stockholders' Equity Attributable to Parent		$ 72,589	$ (455,939)	$ 217	$ 528,307	$ 4

[1] Effective January 1, 2018, we adopted Accounting Standard Update No. 2014-09, Revenue from Contracts with Customers. See Note 2. Significant Accounting Policies and Note 3. Revenue from Contracts with Customers for more information.