Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of stock-based compensation expense recognized

Stock-based compensation expense recognized in the consolidated statements of operations is summarized below:

	Year Ended December 31,
(in thousands)	2018		2017		2016
Cost of goods sold	$	1,140	$	1,692	$	359
Sales and marketing	1,244		640		339
General and administrative	4,990		2,964		1,438
Research and development	1,344		632		388
Total stock-based compensation expense	$	8,718	$	5,928	$	2,524

Schedule of option activity

A summary of option activity for 2018 is presented below:

	Total Stock Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance at January 1, 2018	565,425		$	13.65
Options granted	—		$	—
Options exercised	(192,550	)	$	5.98
Options cancelled and expired	(15,800	)	$	20.44
Outstanding at December 31, 2018	357,075		$	17.50	4.4	535,427
Vested and expected to vest at December 31, 2018	357,075		$	17.50	4.4	535,427
Exercisable at December 31, 2018	353,049		$	17.56	4.4	522,423

Summary of restricted stock awards activity

A summary of TSR Award activity for 2018 is presented below:

	Shares		Weighted- Average Grant Date Fair Value Per Share
Nonvested balance at January 1, 2018	—		$	—
Granted	206,896		$	22.76
Vested	—		$	—
Forfeited	(26,983	)	$	22.76
Nonvested balance at December 31, 2018	179,913		$	22.76

A summary of performance restricted stock award activity for 2018 is presented below:

	Shares		Weighted- Average Grant Date Fair Value Per Share
Nonvested balance at January 1, 2018	291,172		$	16.70
Granted	—		$	—
Vested	—		$	—
Forfeited	(49,292	)	$	16.62
Nonvested balance at December 31, 2018	241,880		$	16.71

A summary of restricted stock awards and restricted stock units activity for 2018 is presented below:

	Shares		Weighted- Average Grant Date Fair Value Per Share
Nonvested balance at January 1, 2018	1,765,262		$	5.72
Granted	647,850		$	15.46
Vested	(672,345	)	$	6.37
Forfeited	(232,228	)	$	11.87
Nonvested balance at December 31, 2018	1,508,539		$	9.51

Schedule of valuation model

The fair value of these awards are based on a Monte Carlo Simulation valuation model with the following assumptions:

	Year Ended December 31,
	2018
Expected volatility	84.3	%
Risk-free interest rate	2.4	%
Expected life (in years)	2.8
Expected dividend yield	—