Lines of Credit and Long-Term Debt - Term Loans (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Dec. 31, 2014	Apr. 30, 2014	Jul. 31, 2011	Jan. 31, 2011	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Lines of Credit and Long-Term Debt
Estimated fair value						$ 5,569
Series B redeemable convertible preferred stock | Preferred Stock Warrant Three
Lines of Credit and Long-Term Debt
Exercise price (in dollars per share)						$ 2.860
Series B redeemable convertible preferred stock | Preferred Stock Warrant Four
Lines of Credit and Long-Term Debt
Exercise price (in dollars per share)						$ 2.990
Tranche A Term Loan
Lines of Credit and Long-Term Debt
Aggregate borrowings				$ 1,265
Fixed rate (as a percent)				6.50%
Frequency of payment				monthly
Periodic payment				$ 25
Interest expense						$ 12	$ 30
Tranche B Term Loan
Lines of Credit and Long-Term Debt
Aggregate borrowings			$ 208
Fixed rate (as a percent)			6.50%
Frequency of payment			monthly
Periodic payment			$ 4
Interest expense					$ 1	3	6
April 2014 Eastward Loan
Lines of Credit and Long-Term Debt
Aggregate borrowings		$ 3,000
Annual rate (as a percent)		11.50%
Interest only payments		$ 29
Period for interest only payments		12 months
Frequency of payment		monthly
Periodic payment		$ 114
Interest expense					112	312	239
Amortization of discount to interest expense					40	95	57
Deferred financing costs		$ 61
Amortization of deferred financing costs to interest expense					9	24	18
April 2014 Eastward Loan | Series B redeemable convertible preferred stock | Preferred Stock Warrant Three
Lines of Credit and Long-Term Debt
Number of shares called by warrant issued		105,005
Exercise price (in dollars per share)		$ 2.86
Aggregate exercise price		$ 300
Estimated fair value		$ 254
December 2014 Eastward Loan
Lines of Credit and Long-Term Debt
Aggregate borrowings	$ 12,000						12,000
Annual rate (as a percent)	12.00%
Interest only payments	$ 120
Period for interest only payments	12 months
Frequency of payment	monthly
Periodic payment	$ 460
Interest expense					643	1,440	4
Amortization of discount to interest expense					316	550	2
Deferred financing costs	$ 150						150
Amortization of deferred financing costs to interest expense					$ 30	$ 64	$ 0
December 2014 Eastward Loan | Series B redeemable convertible preferred stock | Preferred Stock Warrant Four
Lines of Credit and Long-Term Debt
Number of shares called by warrant issued	481,863						481,863
Exercise price (in dollars per share)	$ 2.99						$ 2.99
Aggregate exercise price	$ 1,440						$ 1,440
Estimated fair value	$ 1,581						$ 1,581