Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2013

The following table summarizes stock option activity for the year ended December 31, 2013:


	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value⁽¹⁾
Outstanding at December 31, 2012		7,038,291		$	18.90
Granted		496,216		$	51.06
Exercised		(793,756	)	$	11.18
Forfeited/expired		(126,217	)	$	22.59

Outstanding at December 31, 2013		6,614,534		$	22.12		6.58	$	275.8

Vested and exercisable at December 31, 2013		4,402,561		$	14.85		5.63	$	215.6

(1)

The aggregate intrinsic value is calculated as the pre-tax difference between the weighted-average exercise price of the underlying awards and the closing price per share of $63.82 of the Company’s common stock on December 31, 2013. The calculation excludes any awards with an exercise price higher than the closing price of the Company’s common stock on December 31, 2013. The amounts are presented in millions.

Schedule of Value of Options Vested and Exercised

Additional information regarding stock options is set forth below (in thousands, except per share data):


	Years Ended December 31,
	2013		2012		2011
Intrinsic value of options exercised	$	35,155	$	116,867	$	22,238
Grant-date fair value of options vested	$	22,278	$	10,795	$	12,608
Weighted-average grant-date fair value per share of options granted	$	30.39	$	26.01	$	6.88

Summary of Restricted Stock Units

The following table summarizes restricted stock unit activity for the year ended December 31, 2013:


	Number of Shares			Weighted- Average Grant-Date Fair Value
Unvested at December 31, 2012		373,625		$	39.06
Granted		143,939		$	54.94
Vested		(188,139	)	$	28.09
Forfeited		(18,078	)	$	47.16

Unvested at December 31, 2013		311,347		$	52.57

Summary of Stock Appreciation Rights Activity

The following table summarizes stock appreciation rights activity for the year ended December 31, 2013:


	Number of Rights			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value⁽¹⁾
Outstanding at December 31, 2012		883,600		$	23.91
Granted		—			—
Exercised		(37,442	)	$	23.20
Forfeited		(40,042	)	$	23.20

Outstanding at December 31, 2013		806,116		$	23.98		8.05	$	32.1

Vested and exercisable at December 31, 2013		395,519		$	23.99		8.10	$	15.8

(1)

Schedule of Black-Scholes Assumptions Used for Stock Options and Stock Appreciation Rights

The Black-Scholes assumptions used to estimate the fair value of stock options and stock appreciation rights were as follows:


	Years Ended December 31,
	2013			2012			2011
Expected volatility		64-75	%		66-73	%		71-86	%
Expected term (in years)		5.2-5.5			5.3-5.5			5.6-6.0
Risk-free interest rate		0.73-1.64	%		0.68-1.01	%		1.02-2.34	%
Expected dividend yield		—			—			—

Schedule of Black-Scholes Assumptions Used in Estimating Fair Value of Shares Issued under ESPP

The fair value of shares issued under the ESPP was estimated on the commencement date of the offering period using the Black-Scholes model and the following assumptions:


	Years Ended December 31,
	2013			2012		2011
Expected volatility		45	%		—		—
Expected term (in years)		0.5			—		—
Risk-free interest rate		0.04	%		—		—
Expected dividend yield		—			—		—

Schedule of Stock-Based Compensation Expense

Stock-based compensation expense was as follows:


	Years Ended December 31,
	2013		2012		2011
Stock-based compensation expense recognized as:
R&D expenses	$	16,503	$	11,998	$	8,090
SG&A expenses		20,575		11,680		5,795

Total	$	37,078	$	23,678	$	13,885