Short-Term and Long-Term Debt - Outstanding Convertible Notes Payable Net Carry Value and Estimated Fair Value (Details) - Convertible notes payable - USD ($) $ in Thousands	Jan. 31, 2018	Oct. 31, 2017
Debt Instrument [Line Items]
Net Carrying Value	$ 545,085	$ 543,009
Fair Value	656,306
3.75% Convertible Senior Notes due October 15, 2018 (Original)
Debt Instrument [Line Items]
Net Carrying Value	61,125	61,071
Fair Value	71,778
3.75% Convertible Senior Notes due October 15, 2018 (New)
Debt Instrument [Line Items]
Net Carrying Value	287,627	287,221
Fair Value	338,247
4.0% Convertible Senior Notes due December 15, 2020
Debt Instrument [Line Items]
Net Carrying Value	196,333	$ 194,717
Fair Value	$ 246,281