Financial Assets and Liabilities - Short-term investments (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Oct. 31, 2016
Cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	$ 190,851	$ 504,972
Gross unrealized gains	0	0
Gross unrealized losses less than 12 months	0	0
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	190,851	504,972
Cash equivalents | Money market funds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	188,002	499,274
Gross unrealized gains	0	0
Gross unrealized losses less than 12 months	0	0
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	188,002	499,274
Cash equivalents | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	2,849	1,498
Gross unrealized gains	0	0
Gross unrealized losses less than 12 months	0	0
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	2,849	1,498
Cash equivalents | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		4,200
Gross unrealized gains		0
Gross unrealized losses less than 12 months		0
Gross unrealized losses 12 months or longer		0
Estimated fair value		4,200
Short-term investments
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	138,691	140,676
Gross unrealized gains	37	60
Gross unrealized losses less than 12 months	(80)	(41)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	138,648	140,695
Short-term investments | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	24,831	25,430
Gross unrealized gains	1	1
Gross unrealized losses less than 12 months	0	0
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	24,832	25,431
Short-term investments | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	12,305	13,607
Gross unrealized gains	0	4
Gross unrealized losses less than 12 months	(25)	(8)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	12,280	13,603
Short-term investments | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	20,963	12,849
Gross unrealized gains	0	0
Gross unrealized losses less than 12 months	0	0
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	20,963	12,849
Short-term investments | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	53,806	58,753
Gross unrealized gains	29	43
Gross unrealized losses less than 12 months	(36)	(18)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	53,799	58,778
Short-term investments | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	18,978	22,146
Gross unrealized gains	7	12
Gross unrealized losses less than 12 months	(18)	(12)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	18,967	22,146
Short-term investments | Non-U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	3,401	3,403
Gross unrealized gains	0	0
Gross unrealized losses less than 12 months	(1)	(3)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	3,400	3,400
Short-term investments | Others
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	4,407	4,488
Gross unrealized gains	0	0
Gross unrealized losses less than 12 months	0	0
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	$ 4,407	$ 4,488