Stockholders' equity (Tables)

6 Months Ended

Jun. 30, 2014

Equity [Abstract]

Summary of Restricted Stock Unit Activity

The following table summarizes RSU activity for the six months ended June 30, 2014 (aggregate intrinsic value in thousands):

	Number of Units			Weighted Average Grant- Date Fair Value		Aggregate Intrinsic Value
Units outstanding, beginning of period		1,279,123		$	9.67
Granted		463,196			16.85
Released		(348,171	)		7.43
Forfeited		(135,375	)		12.99
Units outstanding, end of period		1,258,773			12.59	$	16,742

Summary of the Company's Stock Options Activity

The following table summarizes stock option activity for the six months ended June 30, 2014 (aggregate intrinsic value in thousands):

	Number of options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)		Aggregate Intrinsic Value
Options outstanding, beginning of period		3,365,692		$	6.15
Granted		—
Exercised		(1,045,644	)		7.05
Expired / forfeited		(50,134	)		14.97
Options outstanding, end of period		2,269,914			5.65		4.72	$	17,563
Exercisable at June 30, 2014		2,227,102			5.67		4.71	$	17,196
Expected to vest after June 30, 2014		30,076			4.71		5.35	$	259

Share-Based Compensation

Share-based compensation was classified as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2014		2013		2014		2013
Cost of products sold	$	65	$	49	$	88	$	84
Sales, general and administrative expenses		948		827		1,658		1,557
Research and development expenses		494		143		938		302
Total share-based compensation	$	1,507	$	1,019	$	2,684	$	1,943