Stock-Based Compensation (Tables)
 9 Months Ended
Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Schedule of stock option activity
The following table summarizes stock option activity during the year and also presents stock options outstanding and exercisable as of September 30, 2015 (dollars in millions, except for per share data):





Number of
Shares
 
Weighted Average Exercise Price Per Share
Options outstanding at December 31, 2014
4,671,639

 
$
5.88

Granted
110,825

 
$
20.00

Exercised
(334,439
)
 
$
5.70

Forfeited
—

 
$
—

Expired
(5,457
)
 
$
6.12

Options outstanding at September 30, 2015
4,442,568

 
$
6.25

Options exercisable at September 30, 2015
1,498,849

 
$
5.78
Schedule of unrecognized compensation cost
Unrecognized stock-based compensation related to outstanding unvested stock options is expected to be recognized in the Company’s statements of income as follows (by fiscal year):

(dollars in thousands)
 
2015 (period from October 1 through December 31, 2015)
$
485

2016
1,851

2017
1,703

2018
318

2019
125

2020
52

Total
$
4,534
Weighted Average Assumptions

The following are the weighted-average assumptions used for grants issued during the nine month periods ended September 30:
 
2015
 
2014
Volatility
23.85
%
 
32.84
%
Risk-free interest rate
1.88
%
 
2.16
%
Expected term (years)
6.5

 
6.5

Dividend yield
—

 
—

Grant-date fair value
$
5.74

 
$
5.15
Schedule of restricted stock awards activity
The following table summarizes restricted stock activity for the nine months ended September 30, 2015:






Number of
Shares
 
Weighted Average Grant Date Fair Value
Restricted stock awards at December 31, 2014
—

 
$
—

Granted
46,750

 
20.00

Vested
(46,750
)
 
20.00

Forfeited
—

 
—

Restricted stock awards at September 30, 2015
—

 
—