Stock-Based Compensation

9 Months Ended

May 31, 2014

Stock-Based Compensation [Abstract]

Stock-Based Compensation

Note 3. Stock-Based Compensation

The Company accounts for all share-based payments in accordance with ASC Topic 718, "Compensation—Stock Compensation" ("ASC 718").The stock‑based compensation expense related to the stock option plans and the Associate Stock Purchase Plan included in operating expenses was $1,230and $1,329 for the thirteen week periods ended May 31, 2014 and June 1, 2013, respectively, and $4,426 and $4,097 for the thirty-nine week periods ended May 31, 2014 and June 1, 2013, respectively. Tax benefits related to these expenses for the thirteen week periods endedMay 31, 2014 and June 1, 2013were $440 and $483, respectively, and for the thirty-nine week periods ended May 31, 2014 and June 1, 2013were $1,603 and $1,487, respectively.

The fair value of each option grant is estimated on the date of grant using the Black‑Scholes option pricing model with the following assumptions:

	Thirty-Nine Weeks Ended
	May 31,		June 1,
	2014		2013
Expected life (in years)	3.9		3.8
Risk-free interest rate	0.93	%	0.55	%
Expected volatility	26.59	%	32.86	%
Expected dividend yield	1.70	%	1.70	%

A summary of the Company’s stock option activity for the thirty-nineweeks ended May 31, 2014is as follows:

	Options	Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding on August 31, 2013	1,224	$	58.30
Granted	399		81.76
Exercised	(343)		51.25
Canceled	(23)		73.13
Outstanding on May 31, 2014	1,257	$	67.40	4.83	$	30,894
Exercisable on May 31, 2014	436	$	56.18	3.53	$	15,620

The weighted‑average grant-date fair values of the stock options granted for the thirty-nine week periods ended May31, 2014and June 1, 2013were $14.98 and $15.33, respectively.  The unrecognized share‑based compensation cost related to stock option expense at May 31, 2014 was $9,347and will be recognized over a weighted average period of 1.7 years. The total intrinsic value of options exercised, which represents the difference between the exercise price and market value of common stock measured at each individual exercise date, during the thirty-nine week periods ended May 31, 2014and June 1, 2013 were $11,623 and $15,140, respectively.

A  summary of the non‑vested restricted share award activity under the Company’s 2005 Omnibus Incentive Plan (the “Plan”) for the thirty-nine weeks ended May 31, 2014 is as follows:

	Shares	Weighted-Average  Grant-Date Fair Value
Non-vested restricted share awards at August 31, 2013	505	$	59.47
Granted	121		82.20
Vested	(152)		50.22
Canceled/Forfeited	(16)		68.84
Non-vested restricted share awards at May 31, 2014	458	$	68.27

Stock‑based compensation expense recognized for the restricted share awards was $1,979 and $2,024 for the thirteen week periods ended May 31, 2014 and June 1, 2013, respectively, and $6,969 and $6,301 for the thirty-nine week periods ended May 31, 2014 and June 1, 2013, respectively.The unrecognized compensation cost related to restricted share awards granted under the Plan at May 31, 2014 was $17,943 and will be recognized over a weighted average period of 2.2 years. 

A summary of the Company’s non-vested restricted stock unit award activity including dividend equivalent units for the thirty-nine weeks ended May 31, 2014is as follows:

	Shares		Weighted- Average Grant- Date Fair Value
Non-vested restricted stock unit awards at August 31, 2013	196	$	55.32
Granted	3		83.03
Vested	(1)		88.12
Canceled/Forfeited	—		—
Non-vested restricted stock unit awards at May 31, 2014	198	$	55.68

Stock‑based compensation expense recognized for the restricted stock units was $544 and $532 for the thirteen week periods ended May 31, 2014 and June 1, 2013, respectively, and$1,625 and$1,591 for the thirty-nine week periods ended May 31, 2014 and June 1, 2013, respectively.  The unrecognized compensation cost related to the restricted stock units at May 31, 2014was $2,376 and is expected to be recognized over a period of 1.8years.