Earnings Per Share (Basic and Diluted Earnings (Loss) Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	Aug. 31, 2015	Aug. 31, 2014
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	5,700	5,200	5,700	5,200
Numerator:
Net income	$ 23,254	$ 28,361	$ 40,626	$ 65,548
Less: Distributed earnings allocated to nonvested restricted stock	(7)	(6)	(24)	(18)
Less: Undistributed earnings allocated to nonvested restricted stock	(63)	(73)	(115)	(159)
Numerator for basic earnings per share	23,184	28,282	40,487	65,371
Interest expense and amortization of debt issuance costs associated with convertible senior notes, net of taxes	667	667	2,000	2,000
Add: Undistributed earnings allocated to nonvested restricted stock	63	73	115	159
Less: Undistributed earnings reallocated to nonvested restricted stock	(57)	(66)	(104)	(142)
Numerator for diluted earnings per share	$ 23,857	$ 28,956	$ 42,498	$ 67,388
Denominator:
Weighted average shares outstanding — basic	92,065	91,793	92,005	88,389
Effect of dilutive securities: Share-based payments	1,407	1,875	1,198	1,823
Effect of dilutive securities: Convertible senior notes	8,402	8,402	8,402	8,402
Weighted average shares outstanding — diluted	101,874	102,070	101,605	98,614
Basic earnings per share, in dollars per share	$ 0.25	$ 0.31	$ 0.44	$ 0.74
Diluted earnings per share, in dollars per share	$ 0.23	$ 0.28	$ 0.42	$ 0.68