XML 45 R15.htm IDEA: XBRL DOCUMENT v3.19.2
Stock-Based Compensation
6 Months Ended
Jun. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Stock-Based Compensation
7. Stock-Based Compensation

The following table summarizes our stock-based compensation expense (including stock options, restricted stock units ("RSUs") and performance stock units ("PSUs")) for the three and six months ended June 30, 2019 and 2018:


Three Months Ended June 30,
 
Six Months Ended June 30,
(in millions)
2019
 
2018
 
2019
 
2018
Stock option compensation expense
$
0.8

 
$
0.5

 
$
1.3

 
$
1.0

RSU compensation expense
1.9

 
2.0

 
2.9

 
2.9

PSU compensation expense
0.7

 
1.5

 
1.2

 
3.3

Total stock-based compensation expense
$
3.4

 
$
4.0

 
$
5.4

 
$
7.2



We generally recognize compensation expense for stock-based awards ratably over the vesting period. Stock-based compensation expense for each of the three and six months ended June 30, 2019 and 2018 includes $1.0 million and $1.0 million, respectively, of expense related to stock awards granted to eligible non-employee directors, which were fully vested on the grant date.

During the second quarter of 2019, the Company's Board of Directors approved stock compensation grants to executive
officers, which consisted of 204,981 RSUs and 529,496 PSUs. The Board of Directors also approved the annual stock compensation grant to eligible non-employee directors, which consisted of 119,925 RSUs.

The following table summarizes our unrecognized compensation expense and the weighted-average period over which the expense will be recognized as of June 30, 2019:

June 30, 2019

Unrecognized
 
Weighted Average

Compensation
 
Years Expense To Be
(in millions, except weighted average years)
Expense
 
Recognized Over
Stock options
$5.0
 
2.2
RSUs
$8.0
 
2.2
PSUs
$8.3
 
2.2