Earnings (Loss) Per Share (Basic and Diluted Loss Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2011
Numerator:
Net income (loss)	$ 28,116	$ 27,278	$ (2,973)	$ (12,458)	$ 7,724	$ 3,261	$ (24,136)	$ (45,802)	$ 39,963	$ (58,953)	$ (178,768)
Less: Distributed earnings allocated to nonvested restricted stock									(24)	0	0
Less: Undistributed earnings allocated to nonvested restricted stock									90	0	0
Numerator for basic earnings (loss) per share									39,849	(58,953)	(178,768)
Interest expense and amortization of debt issuance costs associated with convertible senior notes, net of taxes									2,230	0	0
Add: Undistributed earnings allocated to nonvested restricted stock									90	0	0
Less: Undistributed earnings reallocated to nonvested restricted stock									(81)	0	0
Numerator for diluted earnings (loss) per share									$ 42,088	$ (58,953)	$ (178,768)
Denominator:
Weighted average shares outstanding — basic									82,630	77,106	77,043
Share-based payments, shares									1,885	0	0
Convertible senior notes, shares									7,044	0	0
Weighted average shares outstanding — diluted									91,559	77,106	77,043
Basic earnings (loss) per share, in dollars per share	$ 0.33	$ 0.32	$ (0.04)	$ (0.16)	$ 0.10	$ 0.04	$ (0.31)	$ (0.59)	$ 0.48	$ (0.76)	$ (2.32)
Diluted earnings (loss) per share, in dollars per share	$ 0.31	$ 0.30	$ (0.04)	$ (0.16)	$ 0.10	$ 0.04	$ (0.31)	$ (0.59)	$ 0.46	$ (0.76)	$ (2.32)