CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit	Total
Beginning balance at Dec. 31, 2013	$ 8	$ 298,593	$ 307	$ (252,211)	$ 46,697
Beginning balances (in shares) at Dec. 31, 2013	78,464
Net loss				8,148	8,148
Stock-based compensation expense		7,073			7,073
Issuance of common stock upon exercise of stock options	$ 1	6,270			$ 6,271
Issuance of common stock upon exercise of stock options (in shares)	2,867				2,867
Issuance of common stock upon exercise of warrants		2,786			$ 2,786
Issuance of common stock upon exercise of warrants (in shares)	1,191
Issuance of common stock as consideration for acquisition	$ 1	61,860			61,861
Issuance of common stock as consideration for acquisition (in shares)	12,832
Taxes paid related to net share settlement of equity awards		(896)			(896)
Taxes paid related to net share settlement of equity awards (in shares)	348
Issuance of common stock pursuant to Employee Stock Purchase Plan		1,076			1,076
Issuance of common stock pursuant to Employee Stock Purchase Plan (in shares)	426
Common stock issued as contingent consideration earned		5,821			5,821
Issuance of common stock as contingent consideration earned (in shares)	1,185
Issuance of common stock, net of issuance costs	$ 1	32,057			32,058
Issuance of common stock (in shares)	9,861
Non-cash warrant expense		1,126			1,126
Other comprehensive income/(loss)			(315)		(315)
Ending balance at Dec. 31, 2014	$ 11	415,766	(8)	(244,063)	171,706
Ending balances (in shares) at Dec. 31, 2014	107,174
Net loss				(7,185)	(7,185)
Stock-based compensation expense		11,686			11,686
Issuance of common stock upon exercise of stock options		3,794			$ 3,794
Issuance of common stock upon exercise of stock options (in shares)	1,440				1,440
Issuance of common stock upon exercise of warrants		676			$ 676
Issuance of common stock upon exercise of warrants (in shares)	450
Taxes paid related to net share settlement of equity awards		(3,018)			(3,018)
Taxes paid related to net share settlement of equity awards (in shares)	1,090
Tax benefits of exercised stock options		107			107
Issuance of common stock pursuant to Employee Stock Purchase Plan		1,655			1,655
Issuance of common stock pursuant to Employee Stock Purchase Plan (in shares)	426
Issuance of common stock, net of issuance costs	$ 2	125,154			125,156
Issuance of common stock (in shares)	21,000
Non-cash warrant expense		1,928			1,928
Other comprehensive income/(loss)			(77)		(77)
Ending balance at Dec. 31, 2015	$ 13	557,748	(85)	(251,248)	306,428
Ending balances (in shares) at Dec. 31, 2015	131,580
Net loss				(87,440)	(87,440)
Stock-based compensation expense		13,263			13,263
Issuance of common stock upon exercise of stock options		294			$ 294
Issuance of common stock upon exercise of stock options (in shares)	270				425
Taxes paid related to net share settlement of equity awards		(2,405)			$ (2,405)
Taxes paid related to net share settlement of equity awards (in shares)	1,401
Issuance of common stock pursuant to Employee Stock Purchase Plan		1,878			1,878
Issuance of common stock pursuant to Employee Stock Purchase Plan (in shares)	750
Non-cash warrant expense		465			465
Other comprehensive income/(loss)			331		331
Ending balance at Dec. 31, 2016	$ 13	$ 571,243	$ 246	$ (338,688)	$ 232,814
Ending balances (in shares) at Dec. 31, 2016	134,001