Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Comprehensive Income [Member]	Director [Member]	Director [Member] Common Stock [Member]
Balance, beginning of year at Nov. 30, 2009	$ 557,867	$ 609	$ 246,656	$ 312,588	$ (1,986)
Balance, beginning of year, shares at Nov. 30, 2009		60,906,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock under employee stock purchase plan, shares		604,000
Issuance of stock under the employee stock purchase plan, value	6,209	6	6,203
Exercise of stock options, shares		6,291,000
Exercise of stock options, value	87,461	63	87,398
Issuance of shares to Board of Directors, shares								24,000
Issuance of shares to Board of Directors, value							0	0
Vesting of restricted stock units, shares		285,000
Vesting of restricted stock units, value	3	3
Withholding tax payments related to net issuance of restricted stock units, shares		(86,000)
Withholding tax payments related to net issuance of restricted stock units, value	(1,859)	(1)	(1,858)
Tax benefit arising from employee stock purchase plan, stock options and restricted share activity	9,463		9,463
Stock-based compensation	18,121		18,121
Treasury stock repurchases and retirements, shares	(1,496,000)	(1,496,000)
Treasury stock repurchases and retirements, value	(29,337)	(15)	(19,045)	(10,277)
Unrealized gain (loss) on investments, net of tax	(207)				(207)	(207)
Net income	48,098			48,098		48,098
Translation adjustment	(5,546)				(5,546)	(5,546)
Comprehensive income						42,345
Balance, end of year at Nov. 30, 2010	690,273	665	346,938	350,409	(7,739)
Balance, end of year, shares at Nov. 30, 2010		66,528,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock under employee stock purchase plan, shares		594,000
Issuance of stock under the employee stock purchase plan, value	6,844	6	6,838
Exercise of stock options, shares		2,755,000
Exercise of stock options, value	42,828	28	42,800
Issuance of shares to Board of Directors, shares								31,000
Issuance of shares to Board of Directors, value							0	0
Vesting of restricted stock units, shares		386,000
Vesting of restricted stock units, value	4	4
Withholding tax payments related to net issuance of restricted stock units, shares		(114,000)
Withholding tax payments related to net issuance of restricted stock units, value	(2,706)	(1)	(2,705)
Tax benefit arising from employee stock purchase plan, stock options and restricted share activity	6,162		6,162
Stock-based compensation	25,999		25,999
Treasury stock repurchases and retirements, shares	(8,391,000)	(8,391,000)
Treasury stock repurchases and retirements, value	(200,009)	(84)	(117,429)	(82,496)
Unrealized gain (loss) on investments, net of tax	354				354	354
Net income	59,629			59,629		59,629
Translation adjustment	(4,268)				(4,268)	(4,268)
Comprehensive income						55,715
Balance, end of year at Nov. 30, 2011	625,110	618	308,603	327,542	(11,653)
Balance, end of year, shares at Nov. 30, 2011	61,788,629	61,789,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock under employee stock purchase plan, shares		376,000
Issuance of stock under the employee stock purchase plan, value	5,654	4	5,650
Exercise of stock options, shares	1,488,000	1,488,000
Exercise of stock options, value	23,435	15	23,420
Vesting of restricted stock units, shares		625,000
Vesting of restricted stock units, value	6	6
Withholding tax payments related to net issuance of restricted stock units, shares		(189,000)
Withholding tax payments related to net issuance of restricted stock units, value	(4,155)	(2)	(4,153)
Tax benefit arising from employee stock purchase plan, stock options and restricted share activity	167	0	167
Stock-based compensation	28,233		28,233
Treasury stock repurchases and retirements, shares	(4,494,000)	(4,494,000)
Treasury stock repurchases and retirements, value	(88,384)	(45)	(62,183)	(26,156)
Unrealized gain (loss) on investments, net of tax	1,527				1,527	1,527
Net income	47,444			47,444		47,444
Translation adjustment	(638)				(638)	(638)
Comprehensive income						48,333
Balance, end of year at Nov. 30, 2012	$ 638,399	$ 596	$ 299,737	$ 348,830	$ (10,764)
Balance, end of year, shares at Nov. 30, 2012	59,594,961	59,595,000