Earnings Per Share (Basic and Diluted Loss Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2015
Numerator:
Net income	$ 84,346	$ 50,208	$ 31,782	$ 14,259	$ 37,528	$ 39,363	$ 15,597	$ 13,127	$ 180,595	$ 105,615	$ 84,643
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic									(56)	(45)	(33)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic									(1,121)	(508)	(273)
Numerator for basic earnings per share									179,418	105,062	84,337
Interest expense and amortization of debt issuance costs associated with convertible senior notes, net of taxes									2,654	2,667	2,667
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted									1,121	508	273
Less: Undistributed earnings reallocated to nonvested restricted stock									(979)	(453)	(244)
Numerator for diluted earnings per share									$ 182,214	$ 107,784	$ 87,033
Denominator:
Weighted average shares outstanding — basic									85,842	85,706	92,054
Share-based payments, shares									4,072	2,170	2,401
Convertible senior notes, shares									8,402	8,402	8,402
Weighted average shares outstanding — diluted									98,316	96,278	102,857
Basic earnings (loss) per share, in dollars per share	$ 0.97	$ 0.58	$ 0.37	$ 0.17	$ 0.44	$ 0.46	$ 0.18	$ 0.15	$ 2.09	$ 1.23	$ 0.92
Diluted earnings (loss) per share, in dollars per share	$ 0.84	$ 0.51	$ 0.33	$ 0.15	$ 0.40	$ 0.42	$ 0.17	$ 0.14	$ 1.85	$ 1.12	$ 0.85