FAIR VALUE MEASUREMENTS (Details 2) - Fair value, Measurements, Recurring - USD ($)
$ in Thousands
Apr. 30, 2017
Oct. 31, 2016
Assets:    
Total assets measured at fair value $ 899,881 $ 1,045,842
Liabilities:    
Total liabilities measured at fair value 2,881 7,363
Cash equivalents    
Assets:    
Total assets measured at fair value 534,423 680,247
Short-term investments    
Assets:    
Total assets measured at fair value 274,779 275,248
Prepaid expenses and other    
Assets:    
Total assets measured at fair value 827 175
Long-term investments    
Assets:    
Total assets measured at fair value 89,852 90,172
Accrued liabilities    
Liabilities:    
Total liabilities measured at fair value 1,811 1,396
Other long-term obligations    
Liabilities:    
Total liabilities measured at fair value 1,070 5,967
Level 1    
Assets:    
Total assets measured at fair value 474,476 625,277
Liabilities:    
Total liabilities measured at fair value 0 0
Level 1 | Cash equivalents    
Assets:    
Total assets measured at fair value 474,476 625,277
Level 1 | Short-term investments    
Assets:    
Total assets measured at fair value 0 0
Level 1 | Prepaid expenses and other    
Assets:    
Total assets measured at fair value 0 0
Level 1 | Long-term investments    
Assets:    
Total assets measured at fair value 0 0
Level 1 | Accrued liabilities    
Liabilities:    
Total liabilities measured at fair value 0 0
Level 1 | Other long-term obligations    
Liabilities:    
Total liabilities measured at fair value 0 0
Level 2    
Assets:    
Total assets measured at fair value 425,405 420,565
Liabilities:    
Total liabilities measured at fair value 2,881 7,363
Level 2 | Cash equivalents    
Assets:    
Total assets measured at fair value 59,947 54,970
Level 2 | Short-term investments    
Assets:    
Total assets measured at fair value 274,779 275,248
Level 2 | Prepaid expenses and other    
Assets:    
Total assets measured at fair value 827 175
Level 2 | Long-term investments    
Assets:    
Total assets measured at fair value 89,852 90,172
Level 2 | Accrued liabilities    
Liabilities:    
Total liabilities measured at fair value 1,811 1,396
Level 2 | Other long-term obligations    
Liabilities:    
Total liabilities measured at fair value 1,070 5,967
Level 3    
Assets:    
Total assets measured at fair value 0 0
Liabilities:    
Total liabilities measured at fair value 0 0
Level 3 | Cash equivalents    
Assets:    
Total assets measured at fair value 0 0
Level 3 | Short-term investments    
Assets:    
Total assets measured at fair value 0 0
Level 3 | Prepaid expenses and other    
Assets:    
Total assets measured at fair value 0 0
Level 3 | Long-term investments    
Assets:    
Total assets measured at fair value 0 0
Level 3 | Accrued liabilities    
Liabilities:    
Total liabilities measured at fair value 0 0
Level 3 | Other long-term obligations    
Liabilities:    
Total liabilities measured at fair value $ 0 $ 0