Stock-Based Compensation (Outstanding and Exercisable Stock Options) (Details) - May. 31, 2015 - $ / shares	Total
Options
Options outstanding at beginning of period, options	11,735,042
Granted, options	0
Exercised, options	(2,000)
Cancelled, options	(63,675)
Options outstanding at end of period, options	11,669,367
Options exercisable at end of period	10,103,406
Weighted Average Exercise Price in dollars per share
Options outstanding at beginning of period, weighted average exercise price in dollars per share	$ 20.45
Granted, weighted average exercise price in dollars per share	0.00
Exercised, weighted average exercise price in dollars per share	12.50
Cancelled, weighted average exercise price in dollars per share	15.53
Options outstanding at end of period, weighted average exercise price in dollars per share	20.48
Options exercisable at end of period	$ 21.32