Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ 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, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2015	Jan. 12, 2016	Jul. 17, 2014	Jan. 29, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares Authorized	290,000,000				290,000,000								290,000,000	290,000,000
Common Stock, Capital Shares Reserved for Future Issuance	12,602,735												12,602,735
Authorized repurchase of common stock									4,000,000						4,000,000
Common Stock, Shares, Issued	117,945,525				116,224,208								117,945,525	116,224,208
Stock repurchases													$ 6,673	$ 88,359	$ 567
Treasury stock, Value													$ 6,673	$ 88,359	567
Stockholder's Equity (Textual) [Abstract]
Number of shares that can be purchased by exercising each right	0.01												0.01
Purchase price for right holders	$ 85.00												$ 85.00
Exercisable options available													earlier of (a) 10 calendar days after a public announcement by us that a person or group has become an Acquiring Person (as defined under the 2009 Rights Agreement) and (b) 10 business days after the commencement of a tender or exchange offer by a person or group if upon consummation of the offer the person or group would beneficially own 4.9% or more of our outstanding common stock.
Calendar days after a public announcement during which rights to be exercised													10 days
Business days after the commencement of a tender or exchange offer during which rights to be exercised													10 days
Beneficially ownership in company's outstanding common stock to be held by person or group to exercise rights													4.90%
Price at which company may redeem all of the then outstanding rights	0.001												$ 0.001
Options under which right issued pursuant to the 2009 rights Agreement will expire													earliest of (a) the close of business on March 5, 2019, (b) the time at which the rights are redeemed, (c) the time at which the rights are exchanged, (d) the time at which our board of directors determines that a related provision in our Restated Certificate of Incorporation is no longer necessary, and (e) the close of business on the first day of a taxable year of ours to which our board of directors determines that no tax benefits may be carried forward. At our annual meeting of stockholders on April 2, 2009, our stockholders approved the 2009 Rights Agreement.
Cash dividend declared per share	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025
Director Plan SARs [Domain]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares Authorized																	680,000
Authorized repurchase of common stock																	680,000
Common Stock, Shares, Issued	0												0
January 2016 Stock Repurchase Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized repurchase of common stock																10,000,000
Treasury Stock, Shares, Acquired														8,373,000
Stock repurchases														$ 85,900
Not Part of a Share Repurchase Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Treasury stock, Value													$ 6,700	$ 2,500	$ 600
Convertible senior notes due February 1, 2019 at 1.375%
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.375%												1.375%					1.375%