v2.4.1.9
Stock-Based Compensation (Tables)
12 Months Ended
Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Schedule of Share-based Compensation, Stock Options, Activity
A summary of stock option activity under the Incentive Plan as of December 31, 2014 and 2013 and changes during the periods then ended are as follows: 
 
 
Number of Shares
 
Weighted-Average Price/Share
 
Weighted-Average Remaining Contractual Term
 
Aggregate Intrinsic Value
 
 
 
 
 
 
(in years)
 
 
Outstanding at December 31, 2012
 
2,820,619

 
$
9.11

 
8.62
 
$
8,687

Granted
 
1,923,206

 
19.46

 
 
 
 
Exercised
 
(588,769
)
 
8.69

 
 
 
 
Cancelled
 
(844,292
)
 
(11.16
)
 
 
 
 
Outstanding at December 31, 2013
 
3,310,764

 
$
14.67

 
8.63
 
$
9,717

Granted
 
3,239,740

 
10.89

 
 
 
 
Exercised
 
(60,632
)
 
8.26

 
 
 
 
Cancelled
 
(1,050,975
)
 
(11.54
)
 
 
 
 
Outstanding at December 31, 2014
 
5,438,897

 
$
13.09

 
8.59
 
$
21

Schedule of Share-based Compensation, Activity
 
 
Number of Shares
 
Weighted-Average Price/Share
 
Weighted-Average Remaining Contractual Term
 
Aggregate Intrinsic Value
 
 
 
 
 
 
(in years)
 
 
Vested and Exercisable at December 31, 2013
 
894,813

 
$
9.38

 
7.61
 
$
5,358

Unvested at December 31, 2013
 
2,415,951

 
16.63

 
7.91
 
 
Vested and Exercisable at December 31, 2014
 
1,248,711

 
$
12.97

 
7.23
 
$

Unvested at December 31, 2014
 
4,190,186

 
13.13

 
9.04
 
 
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions
The fair value of awards granted is estimated at the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions:  
Year of Grant
 
Risk-Free
Interest
Rate
 
Dividend
Yield
 
Expected
Term
 
Volatility
Factor
 
 
 
 
 
 
(in years)
 
 
2012
 
0.71%
 
0%
 
4.40
 
60.0%
2013
 
1.02%
 
0%
 
4.90
 
57.0%
2014
 
1.67%
 
0%
 
5.00
 
53.0%