FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Oct. 31, 2016
Assets:
U.S. government obligations	$ 294,617
Fair value, Measurements, Recurring
Assets:
Money market funds	392,351	$ 625,277
U.S. government obligations	284,634	350,431
Commercial paper	89,887	69,959
Foreign currency forward contracts	1,811	175
Total assets measured at fair value	768,683	1,045,842
Liabilities:
Foreign currency forward contracts	229	1,396
Forward starting interest rate swap	1,396	5,967
Total liabilities measured at fair value	1,625	7,363
Fair value, Measurements, Recurring | Level 1
Assets:
Money market funds	392,351	625,277
U.S. government obligations	0	0
Commercial paper	0	0
Foreign currency forward contracts	0	0
Total assets measured at fair value	392,351	625,277
Liabilities:
Foreign currency forward contracts	0	0
Forward starting interest rate swap	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	284,634	350,431
Commercial paper	89,887	69,959
Foreign currency forward contracts	1,811	175
Total assets measured at fair value	376,332	420,565
Liabilities:
Foreign currency forward contracts	229	1,396
Forward starting interest rate swap	1,396	5,967
Total liabilities measured at fair value	1,625	7,363
Fair value, Measurements, Recurring | Level 3
Assets:
Money market funds	0	0
U.S. government obligations	0	0
Commercial paper	0	0
Foreign currency forward contracts	0	0
Total assets measured at fair value	0	0
Liabilities:
Foreign currency forward contracts	0	0
Forward starting interest rate swap	0	0
Total liabilities measured at fair value	$ 0	$ 0