(Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Nov. 30, 2014	Aug. 31, 2014	May 31, 2014	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2014	Nov. 30, 2013	Nov. 30, 2012
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 199,753	$ 130,083	$ 190,311	$ 131,789	$ 188,668	$ 117,046	$ 178,374	$ 128,552	$ 651,936	$ 612,640	$ 612,367
Operating income	39,838	(3,525)	34,739	22,339	29,532	(13,067)	37,080	25,147	93,391	78,692	105,009
Net income	$ 25,824	$ 191	$ 21,469	$ 19,895	$ 17,205	$ (7,866)	$ 22,440	$ 13,513	$ 67,379	$ 45,292	$ 54,578
Basic and diluted earnings per share	$ 0.55	$ 0.00	$ 0.46	$ 0.43	$ 0.37	$ (0.17)	$ 0.48	$ 0.29