Stock Benefit Plans, Stock-Based Compensation and Equity Transactions - Additional Information (Details)				1 Months Ended				3 Months Ended	12 Months Ended
	Oct. 04, 2016 USD ($) shares	Aug. 24, 2016	Dec. 31, 2011 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Feb. 28, 2015 $ / shares shares	Jul. 31, 2014 $ / shares shares	Oct. 31, 2013 USD ($) Payment $ / shares	Sep. 30, 2016 shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Nov. 02, 2015 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance | shares				2,650,000					2,650,000
Reverse stock split ratio		0.0833							0.0833
Stock-based compensation expense									$ 1,626,000	$ 2,643,000	$ 4,554,000
Collaborative arrangement term							3 years
Collaborative arrangement, number of periodic payments | Payment							3
Collaborative arrangement, periodic payment aggregate amount							$ 8,000,000
Number of days leading up to and including date of signing collaboration agreement for per share price used to calculate annual payments to collaborator							5 days
Number of months of services provided for number of shares issued used to calculate annual payments to collaborator							12 months
Stock-based compensation expense									9,248,000	17,615,000	16,593,000
SiliconValley Bank (SVB)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amendment fee amount waived			$ 200,000
Number of common shares to be called by warrants | shares			7,812
Exercise price of warrants (dollars per share) | $ / shares			$ 19.20
Warrant term			10 years
Collaborative Arrangement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share price | $ / shares							$ 23.35
Additional liability, common stock issued under agreement												$ 6,700,000
Additional liability, common stock issued under agreement, due 2017				$ 2,200,000					2,200,000
Additional liability, common stock issued under agreement, due 2018				2,200,000					2,200,000
Additional liability, common stock issued under agreement, due 2019				$ 2,200,000					$ 2,200,000
Collaborative agreement description									If the Collaborators elect to sell, assign or transfer: (i) more than 20% of the shares issued to the Collaborators prior to the first valuation date; or (ii) any of the Collaborator shares still subject to a lockup after the first valuation date, all of the aforementioned restrictions on transfer and valuation minimums and maximums are null and void.
Collaborative Arrangement | Elite Medical Holdings, LLC and Pac 3 Surgical Products, LLC
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issued | shares				342,356
Stock-based compensation expense									$ 2,100,000	$ 4,900,000	$ 1,900,000
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance | shares				1,155,000					1,155,000
Weighted-average grant-date fair value of stock options granted | $ / shares									$ 4.43	$ 15.36	$ 9.72
Share price | $ / shares				$ 3.21					$ 3.21
Unrecognized compensation expense for stock options and awards expected to be recognized				$ 5,600,000					$ 5,600,000
Straight-line basis over a weighted average period									3 years 7 months 6 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of awards granted | $ / shares									$ 5.79	$ 16.11	$ 16.62
Shares, Awarded | shares									969,000
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense									$ 0	$ 200,000	$ 200,000
2005 Employee, Director and Consultant Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant | shares				615,902					615,902
2005 Employee, Director and Consultant Stock Plan | PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of awards granted | $ / shares					$ 16.20	$ 17.04
Shares, Awarded | shares					154,500	77,666
2005 Employee, Director and Consultant Stock Plan | PRSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage					0.00%	0.00%
2005 Employee, Director and Consultant Stock Plan | PRSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage					200.00%	200.00%
2016 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant | shares				392,659					392,659
Common stock reserved for future issuance | shares								1,083,333
2016 Equity Incentive Plan | Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period								10 years
Award vesting period								4 years
Exercise price minimum percentage of market price on grant date								100.00%
2016 Equity Incentive Plan | Employee Stock Option | 10 Percent Stockholder
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period								5 years
Exercise price minimum percentage of market price on grant date								110.00%
Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance | shares	950,000
Maximum award to be deductible other than options	$ 1,000,000
Inducement Plan | PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity instruments other than options, grants in period, fair value	$ 800,000
Inducement Plan | PRSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target value, vesting percentage	0.00%
Inducement Plan | PRSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target value, vesting percentage	250.00%