XML 28 R18.htm IDEA: XBRL DOCUMENT v3.20.2
Stock-Based Compensation (Tables)
 9 Months Ended
Sep. 24, 2020
Share-based Payment Arrangement [Abstract]  
Stock Option Activity Stock option activity during the thirty-nine weeks ended September 24, 2020 was as follows:
​OptionsWeighted Average Exercise Price
Outstanding at December 27, 20196,037,079 $13.64 
Granted279,504 57.25 
Exercised(2,027,087)7.49 
Forfeited or expired(100,539)25.10 
Outstanding at September 24, 20204,188,957 $19.25 
Vested and exercisable at September 24, 20202,083,405 $11.03 
Estimated Fair Value of Stock Option Grants
The Company estimated the fair value of stock option grants using the Black-Scholes-Merton option pricing model with the following weighted average assumptions during the period:
​Thirty-nine Weeks Ended
​September 24, 2020
Risk-free interest rate1.21 %
Expected volatility38.7 %
Expected life (in years)5.75
Dividend yield— %
Restricted Stock Unit Activity
The following table summarizes restricted stock unit activity during the thirty-nine weeks ended September 24, 2020:
Restricted Stock Units
Unvested at December 27, 2019— 
Granted115,765 
Vested— 
Forfeited(3,728)
Unvested at September 24, 2020112,037 
Restricted Stock Award Activity
The following table summarizes restricted stock award activity during the thirty-nine weeks ended September 24, 2020:
Restricted Stock Awards
Service-basedPerformance-basedTSR
Unvested at December 27, 201937,032 — — 
Granted102,931 160,315 104,456 
Vested(3,870)— — 
Forfeited— — — 
Unvested at September 24, 2020136,093 160,315 104,456