Fair Value Measurements (Details) - USD ($) $ in Thousands	Jan. 31, 2019	Oct. 31, 2018
Liabilities:
Debt conversion liability	$ 0	$ 164,212
Fair value, Measurements, Recurring
Assets:
Money market funds	530,110	590,684
U.S. government obligations	119,143	197,988
Commercial paper	19,998	69,888
Total assets measured at fair value	669,303	859,472
Liabilities:
Debt conversion liability		164,212
Contingent consideration	10,900	10,900
Total liabilities measured at fair value	20,571	178,343
Fair value, Measurements, Recurring | Level 1
Assets:
Money market funds	530,110	590,684
U.S. government obligations	0	0
Commercial paper	0	0
Total assets measured at fair value	530,110	590,684
Liabilities:
Debt conversion liability		0
Contingent consideration	0	0
Total liabilities measured at fair value	0	0
Fair value, Measurements, Recurring | Level 2
Assets:
Money market funds	0	0
U.S. government obligations	119,143	197,988
Commercial paper	19,998	69,888
Total assets measured at fair value	139,193	268,788
Liabilities:
Debt conversion liability		164,212
Contingent consideration	0	0
Total liabilities measured at fair value	9,671	167,443
Fair value, Measurements, Recurring | Level 3
Assets:
Money market funds	0	0
U.S. government obligations	0	0
Commercial paper	0	0
Total assets measured at fair value	0	0
Liabilities:
Debt conversion liability		0
Contingent consideration	10,900	10,900
Total liabilities measured at fair value	10,900	10,900
Foreign Currency Forward Contracts | Fair value, Measurements, Recurring
Assets:
Derivative asset	52	133
Liabilities:
Derivative liability	1,587	3,231
Foreign Currency Forward Contracts | Fair value, Measurements, Recurring | Level 1
Assets:
Derivative asset	0	0
Liabilities:
Derivative liability	0	0
Foreign Currency Forward Contracts | Fair value, Measurements, Recurring | Level 2
Assets:
Derivative asset	52	133
Liabilities:
Derivative liability	1,587	3,231
Foreign Currency Forward Contracts | Fair value, Measurements, Recurring | Level 3
Assets:
Derivative asset	0	0
Liabilities:
Derivative liability	0	0
Forward Starting Interest Rate Swaps | Fair value, Measurements, Recurring
Assets:
Derivative asset		779
Liabilities:
Derivative liability	8,084
Forward Starting Interest Rate Swaps | Fair value, Measurements, Recurring | Level 1
Assets:
Derivative asset		0
Liabilities:
Derivative liability	0
Forward Starting Interest Rate Swaps | Fair value, Measurements, Recurring | Level 2
Assets:
Derivative asset		779
Liabilities:
Derivative liability	8,084
Forward Starting Interest Rate Swaps | Fair value, Measurements, Recurring | Level 3
Assets:
Derivative asset		$ 0
Liabilities:
Derivative liability	$ 0