Stock-Based Compensation

3 Months Ended

Feb. 28, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

Stock-Based Compensation

Stock Options. We estimate the grant-date fair value of stock options using the Black-Scholes option-pricing model. The following table summarizes stock option transactions for the three months endedFebruary 28, 2017:

	Options		Weighted Average Exercise Price
Options outstanding at beginning of period	12,731,545		$	18.95
Granted	—		—
Exercised	(74,854	)	8.85
Cancelled	(124,090	)	19.46
Options outstanding at end of period	12,532,601		$	19.01
Options exercisable at end of period	10,307,866		$	19.78

As of February 28, 2017, the weighted average remaining contractual life of stock options outstanding and stock options exercisable was 4.3 years and 3.3 years, respectively. There was $3.5 million of total unrecognized compensation expense related to unvested stock option awards as of February 28, 2017 that is expected to be recognized over a weighted average period of 1.5 years. For the three months ended February 28, 2017 and February 29, 2016, stock-based compensation expense associated with stock options totaled $.8 million and $.9 million, respectively. The aggregate intrinsic values of stock options outstanding and stock options exercisable were $38.4 million and $33.3 million, respectively, at February 28, 2017. (The intrinsic value of a stock option is the amount by which the market value of a share of the underlying common stock exceeds the exercise price of the stock option.)

Other Stock-Based Awards. From time to time, we grant restricted stock and PSUs to various employees as a compensation benefit. We recognized total compensation expense of $2.3 million for the three months ended February 28, 2017 and $1.9 million for the three months ended February 29, 2016 related to restricted stock and PSUs.