Fair Value Measurements - Balance Sheet Items (Details) - USD ($)
$ in Thousands
Oct. 01, 2018
Oct. 31, 2018
Aug. 30, 2018
Oct. 31, 2017
Liabilities:        
Debt conversion liability   $ 164,212 $ 152,100 $ 0
Fair Value, Measurements, Recurring        
Assets:        
Total assets measured at fair value   859,472   900,641
Liabilities:        
Debt conversion liability   164,212    
Total liabilities measured at fair value   178,343   2,129
Fair Value, Measurements, Recurring | Cash equivalents        
Assets:        
Cash equivalents   650,609   571,280
Fair Value, Measurements, Recurring | Short-term investments        
Assets:        
Short-term investments   148,981   279,133
Fair Value, Measurements, Recurring | Prepaid expenses and other        
Assets:        
Prepaid expenses and other   133   227
Fair Value, Measurements, Recurring | Long-term investments        
Assets:        
Long-term investments   58,970   49,783
Fair Value, Measurements, Recurring | Other long-term assets        
Assets:        
Other long-term assets   779   218
Fair Value, Measurements, Recurring | Accrued liabilities        
Liabilities:        
Accrued liabilities   3,231   2,129
Fair Value, Measurements, Recurring | Debt conversion liability        
Liabilities:        
Debt conversion liability   164,212    
Fair Value, Measurements, Recurring | Other long-term obligations        
Liabilities:        
Other long-term obligations   10,900    
Fair Value, Measurements, Recurring | Level 1        
Assets:        
Total assets measured at fair value   590,684   511,355
Liabilities:        
Debt conversion liability   0    
Total liabilities measured at fair value   0   0
Fair Value, Measurements, Recurring | Level 1 | Cash equivalents        
Assets:        
Cash equivalents   590,684   511,355
Fair Value, Measurements, Recurring | Level 1 | Short-term investments        
Assets:        
Short-term investments   0   0
Fair Value, Measurements, Recurring | Level 1 | Prepaid expenses and other        
Assets:        
Prepaid expenses and other   0   0
Fair Value, Measurements, Recurring | Level 1 | Long-term investments        
Assets:        
Long-term investments   0   0
Fair Value, Measurements, Recurring | Level 1 | Other long-term assets        
Assets:        
Other long-term assets   0   0
Fair Value, Measurements, Recurring | Level 1 | Accrued liabilities        
Liabilities:        
Accrued liabilities   0   0
Fair Value, Measurements, Recurring | Level 1 | Debt conversion liability        
Liabilities:        
Debt conversion liability   0    
Fair Value, Measurements, Recurring | Level 1 | Other long-term obligations        
Liabilities:        
Other long-term obligations   0    
Fair Value, Measurements, Recurring | Level 2        
Assets:        
Total assets measured at fair value   268,788   389,286
Liabilities:        
Debt conversion liability   164,212    
Total liabilities measured at fair value   167,443   2,129
Fair Value, Measurements, Recurring | Level 2 | Cash equivalents        
Assets:        
Cash equivalents   59,925   59,925
Fair Value, Measurements, Recurring | Level 2 | Short-term investments        
Assets:        
Short-term investments   148,981   279,133
Fair Value, Measurements, Recurring | Level 2 | Prepaid expenses and other        
Assets:        
Prepaid expenses and other   133   227
Fair Value, Measurements, Recurring | Level 2 | Long-term investments        
Assets:        
Long-term investments   58,970   49,783
Fair Value, Measurements, Recurring | Level 2 | Other long-term assets        
Assets:        
Other long-term assets   779   218
Fair Value, Measurements, Recurring | Level 2 | Accrued liabilities        
Liabilities:        
Accrued liabilities   3,231   2,129
Fair Value, Measurements, Recurring | Level 2 | Debt conversion liability        
Liabilities:        
Debt conversion liability   164,212    
Fair Value, Measurements, Recurring | Level 2 | Other long-term obligations        
Liabilities:        
Other long-term obligations   0    
Fair Value, Measurements, Recurring | Level 3        
Assets:        
Total assets measured at fair value   0   0
Liabilities:        
Debt conversion liability   0    
Total liabilities measured at fair value   10,900   0
Fair Value, Measurements, Recurring | Level 3 | Cash equivalents        
Assets:        
Cash equivalents   0   0
Fair Value, Measurements, Recurring | Level 3 | Short-term investments        
Assets:        
Short-term investments   0   0
Fair Value, Measurements, Recurring | Level 3 | Prepaid expenses and other        
Assets:        
Prepaid expenses and other   0   0
Fair Value, Measurements, Recurring | Level 3 | Long-term investments        
Assets:        
Long-term investments   0   0
Fair Value, Measurements, Recurring | Level 3 | Other long-term assets        
Assets:        
Other long-term assets   0   0
Fair Value, Measurements, Recurring | Level 3 | Accrued liabilities        
Liabilities:        
Accrued liabilities   0   $ 0
Fair Value, Measurements, Recurring | Level 3 | Debt conversion liability        
Liabilities:        
Debt conversion liability   0    
Fair Value, Measurements, Recurring | Level 3 | Other long-term obligations        
Liabilities:        
Other long-term obligations   $ 10,900    
DonRiver Holdings, LLC        
Liabilities:        
Contingent consideration agreement term 3 years