Fair value of financial instruments (Tables)

6 Months Ended

Jun. 30, 2015

Methodologies and significant inputs used in the determination of the fair value

Hierarchy for financial instruments measured at fair value on a recurring basis

	Fair Value as of December 31, 2014
	Level 1		Level 2		Level 3		Total
	(in thousands)
Cash and cash equivalents	$	13,343	$	—	$	—	$	13,343
Short term investments	3,000		—		—		3,000
Earnout liability	—		—		756		756
Series C Redeemable Preferred Stock Warrants	—		—		1,789		1,789
	$	16,343	$	—	$	2,545	$	18,888

	Fair Value as of June 30, 2015
	Level 1		Level 2		Level 3		Total
	(in thousands)
Cash and cash equivalents	$	25,631	$	—	$	—	$	25,631
Short term investments	—		—		—		—
Earnout liability	—		—		356		356
Series C Redeemable Preferred Stock Warrants	—		—		3,934		3,934
	$	25,631	$	—	$	4,290	$	29,921

Changes in Level 3 liabilities measured at fair value

				Series C Warrants		Series C Warrants Issued
	Earnout			Issued With		With Series C Redeemable
	Liability			Senior Debt		Preferred Stock Financing
	(in thousands)
Balance at December 31, 2014	$	756		$	454	$	1,335
Additions during the period	—			—		2,131
Changes in fair value	(400		)	119		176
Warrants exercised	—			—		(281		)
Balance at June 30, 2015	$	356		$	573	$	3,361

Earnout liability

Methodologies and significant inputs used in the determination of the fair value

Methodologies and significant inputs used in determination of fair value

	December 31, 2014		March 31, 2015		June 30, 2015
	Earnout Liability		Earnout Liability		Earnout Liability
	(Dollars in thousands)
Date of Valuation	12/31/2014		3/31/2015		6/30/2015
Valuation Method	Monte Carlo		Monte Carlo		Monte Carlo
Volatility (annual)	50%		50%		50%
Risk-free rate (annual)	.15% - 3.21%		.14% - 3.00%		.09% - 3.51%
Time period from valuation until end of earnout	.5 - 9.5		.375 - 9.375		.25 - 9.0
Earnout Target 1	$	13,700	$	13,700	$	13,700
Earnout Target 2	$	18,200	$	18,200	$	18,200
Discount rate	7.96% - 11.03%		8.18% - 11.04%		7.96% - 11.39%
Fair value of liability at valuation date	$	756	$	314	$	356

Series C Warrants Issued with Senior Debt | Derivative liability

Methodologies and significant inputs used in the determination of the fair value

Methodologies and significant inputs used in determination of fair value

	Revalue Series C		Revalue Series C		Revalue Series C
	Warrants Issued with		Warrants Issued with		Warrants Issued with
	Senior Debt at		Senior Debt at		Senior Debt at
	December 31, 2014		March 31, 2015		June 30, 2015
	(Dollars in thousands, except $5 Exercise Price)
Date of Valuation	12/31/2014		3/31/2015		6/30/2015
Valuation Method	PWERM and Option Pricing		PWERM and Option Pricing		PWERM and Option Pricing
Dividend yield (per share)	0		0		0
Exercise price	$ 5		$ 5		$ 5
Volatility (annual)	60%		60%		60%
Risk-free rate (annual)	.25% - 2.47%		.19% - 2.31%		.14% - 2.83%
Contractual term (years)	1 - 5		.75 - 5		.5 - 5
Number of warrants	170,000		170,000		170,000
Fair value of liability at valuation date	$	454	$	486	$	573

Series C Warrants Issued with Series C Redeemable Preferred Stock Financing | Derivative liability

Methodologies and significant inputs used in the determination of the fair value

Methodologies and significant inputs used in determination of fair value

	Initial Valuation of
	December 31, 2014	Initial Valuation	Initial Valuation	Revalue All Warrants	Revalue All Warrants
	Warrants Issued	of January 2015	of February 2015	Issued With Series C	Issued With Series C
	With Series C	Warrants Issued With	Warrants Issued With	Redeemable Preferred	Redeemable Preferred
	Redeemable	Series C Redeemable	Series C Redeemable	Stock at	Stock at
	Preferred Stock	Preferred Stock	Preferred Stock	March 31, 2015	June 30, 2015
	(Dollars in thousands, except $5 Exercise Price)
Date of Valuation	12/31/2014	1/31/2015	2/28/2015	3/31/2015	6/30/2015
Valuation Method	PWERM and Option Pricing	PWERM and Option Pricing	PWERM and Option Pricing	PWERM and Option Pricing	PWERM and Option Pricing
Dividend yield (per share)	0	0	0	0	0
Exercise price	$ 5	$ 5	$ 5	$ 5	$ 5
Volatility (annual)	60%	60%	60%	60%	60%
Risk-free rate (annual)	.25% - 2.47%	.25% - 2.47%	.25% - 2.47%	.19% - 2.31%	.14% - 2.83%
Contractual term (years)	1 - 5	1 - 5	1 - 5	.75 - 5	.5 - 5
Number of warrants	749,967	590,906	606,312	1,947,185	1,797,185
Fair value of liability at valuation date	$ 1,335	$ 1,052	$ 1,079	$ 3,233	$ 3,361