Stockholders' Equity (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2013

Dec. 31, 2012

Authorized and Outstanding Convertible Preferred Stock

Authorized and outstanding Series A, Series B, Series C, Series C-1, Series D, Series E and Series F convertible preferred stock (collectively, preferred stock) as of December 31, 2012 are as follows:

			Shares
Convertible Preferred Stock	Net Carrying Amount (In Thousands)		Authorized		Issued and Outstanding
Series A	$	30		181,722		45,430
Series B		4,744		10,411,625		2,602,903
Series C		11,931		13,650,896		3,412,719
Series C-1		4,725		5,682,948		1,420,730
Series D		14,910		17,062,711		4,265,676
Series E		20,210		18,436,763		4,609,185
Series F		56,718		21,300,000		5,087,608
	$	113,268		86,726,665		21,444,251

Weighted Average Assumptions for Options Granted

The following table presents the weighted-average assumptions for options granted during the periods presented:

	Six Months Ended June 30,
	2012			2013
	(unaudited)
Expected term (in years)		6.3			6.2
Risk-free interest rate		1.37	%		1.02	%
Dividend yield		None			None
Volatility rate		42	%		44	%

The following table presents the weighted-average assumptions used to estimate the fair value of the stock options granted in the Company’s consolidated financial statements:

	Year Ended December 31,
	2010			2011			2012
Expected term (in years)		6.2			5.8			6.3
Risk-free interest rate		2.90	%		1.73	%		1.26	%
Dividend yield		None			None			None
Volatility rate		47	%		39	%		42	%

Stock Option Activity and Related Information

Stock option activity and related information during the period indicated was as follows (unaudited):

	Options Outstanding			Weighted- Average Exercise Price		Options Exercisable		Exercisable Weighted- Average Exercise Price
Outstanding at December 31, 2012		6,730,520		$	5.10		3,352,116	$	2.20
Granted		354,250			20.82
Exercised		(265,560	)		2.02
Forfeited		(88,749	)		10.34
Outstanding at June 30, 2013		6,730,461		$	5.98		3,694,041	$	2.94

The Company’s stock option activity and related information under the 2010 Plan was as follows:

	Options Outstanding			Weighted Average Exercise Price		Options Exercisable		Exercisable Weighted Average Exercise Price
Outstanding at December 31, 2011		4,278,806		$	2.57		2,716,392	$	1.56
Granted		2,578,821			9.28
Exercised		(56,367	)		2.58
Forfeited		(70,740	)		6.12
Outstanding at December 31, 2012		6,730,520		$	5.10		3,352,116	$	2.20

Summary of Options Outstanding

The summary of options outstanding as of December 31, 2012 is shown below:

	Outstanding Options				Options Exercisable
Exercise Price	Number Outstanding		Weighted Average Remaining Contractual Life (Years)		Number Exercisable		Weighted Average Remaining Contractual Life (Years)
$  0.20		15,000		1.93		15,000		1.93
0.40		8,750		2.17		8,750		2.17
0.68		1,397,665		3.68		1,397,665		3.68
1.00		653,066		5.08		653,066		5.08
2.00		64,984		5.85		63,706		5.84
2.64		107,500		6.65		88,953		6.64
4.48		1,937,809		7.59		1,029,280		7.41
6.84		1,620,746		9.15		74,915		8.93
12.72		353,750		9.39		20,781		9.39
14.12		571,250		9.63		—		—
		6,730,520		7.13		3,352,116		5.36