Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2013

Stockholders' Equity

Summary of warrants exercised to purchase common stock

	Number of
	Stock
	Warrants
Outstanding at beginning of the year	25,617
Exercised	(2,840		)
Issued	—
Cancelled	—
Outstanding at end of the period	22,777
Weighted average exercise price	$	7.48

Summary of status of stock options issued pursuant to the plans

Options	Number of Shares		Weighted Average Exercise Price		Weighted Average Contractual Life (years)
Outstanding at beginning of the year	6,854,369		$	7.92
Granted	391,275		$	14.29
Forfeited	(31,671	)	$	10.48
Exercised	(100,671	)	$	2.97
Outstanding at end of the period	7,113,302		$	8.33	7.5
Exercisable at end of the period	3,849,690		$	5.06	6.4
Available for future grants at March 31, 2013	173,682

Summary of intrinsic values of options outstanding, vested and exercised

	2013
	Number of	Intrinsic
	Options	Value
Outstanding	7,113,302	$	37,296,821
Vested	3,849,690	$	29,926,026
Exercised	100,671	$	1,133,058

Summary of status of restricted stock units issued pursuant to the plans

Restricted Stock Units	Number of Shares		Weighted Average Fair Value
Outstanding at beginning of the year	221,314		$	17.27
Granted	519,034		$	14.93
Vested	(37,957	)	$	16.29
Outstanding at end of the period	702,391		$	15.59

Schedule of total compensation expense for stock-based compensation awards included in the accompanying condensed consolidated statements of operations

In accordance with ASC 718, Share Based Payment (“ASC 718”), total compensation expense for stock-based compensation awards was $1.6 million and $3.1 million for the three months ended March 31, 2012 and 2013, respectively, which is included on the accompanying condensed consolidated statements of operations as follows (in thousands):

	Three Months Ended
	March 31,
	2012		2013
Cost of goods sold	$	250	$	554
Sales and marketing expenses	366		813
General and administrative expenses	915		1,472
Research and development	93		260
Total stock-based employee compensation	$	1,624	$	3,099

Schedule of stock-based employee compensation expense for equity awards granted

Stock-based employee compensation expense for equity awards granted since January 1, 2006 will be recognized over the following periods as follows (in thousands):

Years Ending December 31,
2013	$	9,091
2014	10,865
2015	7,701
2016	2,095
2017	92
	$	29,844

Schedule of valuation assumptions used to determine value of options granted during the year using Black-Scholes valuation model

	2013
Expected dividend yield	0%
Risk-free interest rate	1.04% to 1.14%
Expected term (in years)	5.8 - 6.1 years
Expected volatility	56.34% - 56.38%