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Employee Stock-Based Compensation
 6 Months Ended
Jun. 30, 2013
Share-based Compensation [Abstract]  
Employee Stock-Based Compensation
Employee Stock-Based Compensation
We currently grant stock options and restricted stock units to employees and directors under our 2010 Equity Incentive Plan. Additionally, through our 2010 Employee Stock Purchase Plan, employees are able to purchase shares of our Class A common stock at a discount through payroll deductions. We have reserved shares of our Class A common stock for issuance under these plans.
The following table summarizes stock options and restricted stock units granted under our 2010 Equity Incentive Plan:
 
Six Months Ended June 30,
 
2013
 
2012
 
(In thousands, except per share data)
Stock options granted
1,588

 
976

Weighted-average exercise price
$
16.57

 
$
27.93

Weighted-average grant-date fair value
$
5.55

 
$
13.03

 
 
 
 
Restricted stock units granted
497

 
53

Weighted-average grant-date fair value
$
16.55

 
$
28.70

Note 6—Employee Stock-Based Compensation (continued)
We estimated the fair value of each stock option grant on the date of grant using the following weighted-average assumptions:
 
Six Months Ended June 30,
 
2013
 
2012
Risk-free interest rate
0.90
%
 
1.12
%
Expected term (life) of options (in years)
5.49

 
6.05

Expected dividends
—

 
—

Expected volatility
43.72
%
 
48.26
%

The total stock-based compensation expense recognized was $6.5 million and $6.6 million for the six-month periods ended June 30, 2013 and 2012, respectively. Total stock-based compensation expense includes amounts related to awards of stock options and restricted stock units and purchases under our 2010 Employee Stock Purchase Plan.