Income Per Share Information (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Oct. 31, 2016	Sep. 05, 2012
Earnings Per Share [Abstract]
Net income as reported	$ 70,416	$ 73,180	$ 382,095
Interest and costs attributable to 0.5% Exchangeable Senior Notes, net of income tax benefit	384	389
Numerator for diluted earnings per share	$ 70,800	$ 73,569
Basic weighted-average shares	162,588	174,205
Common stock equivalents	1,971	2,328
Shares attributable to 0.5% Exchangeable Senior Notes	5,858	5,858
Diluted weighted-average shares	170,417	182,391
Debt Instrument [Line Items]
Shares issued under stock incentive and employee stock purchase plans	1,280	473
0.5% Exchangeable Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				0.50%
Restricted Stock Units RSU And Employee Stock Option Member [Member]
Debt Instrument [Line Items]
Weighted-average number of antidilutive options and restricted stock units	5,204	2,954