Quarterly Results of Operations (Unaudited) (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. 28, 2012	Nov. 30, 2013	Nov. 30, 2012	Nov. 30, 2011
Selected Quarterly Financial Information [Abstract]
Revenue	$ 559,675	$ 480,288	$ 418,143	$ 382,525	$ 414,358	$ 385,609	$ 387,159	$ 342,743	$ 1,840,631	$ 1,529,869	$ 1,325,638
Cost of revenue	217,406	198,279	172,424	160,075	158,907	153,746	165,271	146,590	748,184	624,514	558,492
Net income	$ 40,810	$ 23,362	$ 42,890	$ 24,671	$ 46,420	$ 44,082	$ 44,191	$ 23,475	$ 131,733	$ 158,168	$ 135,415
Earnings per share:
Earnings Per Share, Basic	$ 0.61	$ 0.35	$ 0.65	$ 0.37	$ 0.70	$ 0.67	$ 0.67	$ 0.36	$ 1.98	$ 2.40	$ 2.09
Earnings Per Share, Diluted	$ 0.60	$ 0.35	$ 0.65	$ 0.37	$ 0.69	$ 0.66	$ 0.66	$ 0.35	$ 1.95	$ 2.37	$ 2.06