Share-Based Compensation
 3 Months Ended
May 05, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Share-Based Compensation
Share-Based Compensation
Equity Incentive Plan
Pursuant to the Company's 2002 Equity Incentive Plan (the “Plan”), the Company’s board of directors may grant stock options, restricted shares, and restricted stock units to officers, directors, key employees and professional service providers. The Plan, as amended, allows for the issuance of up to a total of 7,600,000 shares under the Plan. As of May 5, 2018, 3,255,632 stock options, restricted shares, or restricted stock units were available for grant.
Common Stock Options
All stock options have a term not greater than ten years. Stock options vest and become exercisable in whole or in part, in accordance with vesting conditions set by the compensation committee of the Company’s board of directors. Options granted to date generally vest over four years from the date of grant.
Stock option activity under the Plan was as follows:
 
Options
Outstanding
 
Weighted
Average
Exercise
Price
 
Weighted
Average
Remaining
Contractual
Term
(in years)
Balance as of February 3, 2018
519,485

 
$
29.53

 
5.9
Exercised
(39,237
)
 
31.21

 

Balance as of May 5, 2018
480,248

 
29.39

 
5.7
Exercisable as of May 5, 2018
391,582

 
$
28.30

 
5.4
The fair value of each option award granted to employees, including outside directors, is estimated on the date of grant using the Black-Scholes option-pricing model. There were no stock options granted during the thirteen weeks ended May 5, 2018.
Restricted Stock Units and Performance-Based Restricted Stock Units
All restricted stock units ("RSU") and performance-based restricted stock units ("PSU") vest in accordance with vesting conditions set by the compensation committee of the Company’s board of directors. RSU's granted to date have vesting periods ranging from less than one year to five years from the date of grant. PSU's granted to date have vesting periods ranging from one year to five years from the date of grant, including grants that have a cumulative three year performance period, subject to satisfaction of the applicable performance goals established for the respective grant. The Company periodically assesses the probability of achievement of the performance criteria and adjusts the amount of compensation expense accordingly. Compensation is recognized over the vesting period and adjusted for the probability of achievement of the performance criteria.
RSU and PSU activity during the thirteen weeks ended May 5, 2018 was as follows:
 
Restricted Stock Units
 
Performance-Based Restricted Stock Units
 
Number
 
Weighted-Average Grant Date Fair Value
 
Number
 
Weighted-Average Grant Date Fair Value
Non-vested balance as of February 3, 2018
309,554

 
$
38.48

 
495,659

 
$
37.43

Granted
86,692

 
68.98

 
119,056

 
68.98

Vested
(54,395
)
 
35.66

 
(189,350
)
 
36.00

Forfeited
(3,763
)
 
39.83

 
—

 
—

Non-vested balance as of May 5, 2018
338,088

 
$
46.74

 
425,365

 
$
46.89


In connection with the vesting of RSU's and PSU's during the thirteen weeks ended May 5, 2018, the Company withheld 101,928 shares with an aggregate value of $6.9 million in satisfaction of minimum tax withholding obligations due upon vesting.
As of May 5, 2018, there was $22.2 million of total unrecognized compensation costs related to non-vested share-based compensation arrangements (including stock options, restricted stock units and performance-based restricted stock units) granted under the Plan. The cost is expected to be recognized over a weighted average vesting period of 2.6 years.