Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

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)	2017		2016		2015
Cost of goods sold	$	1,692	$	359	$	192
Sales and marketing	640		339		254
General and administrative	2,964		1,438		1,330
Research and development	632		388		226
Total stock-based compensation expense	$	5,928	$	2,524	$	2,002

Schedule of Assumptions used in Valuing Stock Options Granted

The table below summarizes the key assumptions used in valuing stock options granted:

	Year Ended December 31, 2015
Expected volatility	26.0% - 30.0%
Expected dividends	—
Expected life (in years)	4.1 - 6.3
Risk-free interest rate	1.3% - 1.9%

Summary of Option Activity

A summary of option activity for 2017 is presented below:

	Time Based		Performance Based		Total Stock Options		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance at January 1, 2017	818,331		219,006		1,037,337		$	10.63
Options granted	—		—		—		$	—
Options exercised	(338,133	)	(127,099	)	(465,232	)	$	6.98
Options forfeited and expired	(2,565	)	(4,115	)	(6,680	)	$	9.47
Outstanding at December 31, 2017	477,633		87,792		565,425		$	13.65	3.9	$	4,150,751
Vested and expected to vest at December 31, 2017	477,633		87,792		565,425		$	13.65	3.9	$	4,150,751
Exercisable at December 31, 2017	371,861		87,792		459,653		$	14.94	4.4	$	2,774,300

Summary of Restricted Stock Awards Activity

A summary of performance restricted stock award activity for 2017 is presented below:

	Shares		Weighted- Average Grant Date Fair Value Per Share
Nonvested performance restricted stock, January 1, 2017	—		$	—
Granted	303,495		$	16.69
Vested	—		$	—
Cancelled	(12,323	)	$	16.62
Nonvested performance restricted stock, December 31, 2017	291,172		$	16.70

A summary of restricted stock awards activity for 2017 is presented below:

	Shares		Weighted- Average Grant Date Fair Value Per Share
Nonvested restricted stock, January 1, 2017	2,156,372		$	3.71
Granted	395,146		$	12.94
Vested	(744,244	)	$	3.86
Cancelled	(42,012	)	$	3.78
Nonvested restricted stock, December 31, 2017	1,765,262		$	5.72