Earnings Per Share Calculation - Earnings Per Share Calculation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Numerator
Net income (loss)	$ 52,738	$ 13,856	$ 86,354	$ (459,507)
Denominator
Basic weighted average shares outstanding (in shares)	156,170	143,975	156,244	143,948
Add: Shares underlying outstanding stock options and restricted stock units and issuable under employee stock purchase plan (in shares)	2,119	1,345	1,967	0
Dilutive weighted average shares outstanding (in shares)	158,289	147,973	158,211	143,948
EPS
Basic EPS (in dollars per share)	$ 0.34	$ 0.10	$ 0.55	$ (3.19)
Diluted EPS (in dollars per share)	$ 0.33	$ 0.09	$ 0.55	$ (3.19)
3.75% Convertible Senior Notes due October 15, 2018 (New)
Denominator
Add: Shares underlying 3.75% Convertible Senior Notes due 2018 (New) (in shares)	0	2,653	0	0