Financial Assets and Liabilities - Short-term investments (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Oct. 31, 2016
Cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	$ 400,189	$ 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	400,189	504,972
Cash equivalents | Money market funds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	392,191	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	392,191	499,274
Cash equivalents | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	3,448	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	3,448	1,498
Cash equivalents | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	2,000
Gross unrealized gains	0
Gross unrealized losses less than 12 months	0
Gross unrealized losses 12 months or longer	0
Estimated fair value	2,000
Cash equivalents | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	1,000	4,200
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	1,000	4,200
Cash equivalents | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	1,550
Gross unrealized gains	0
Gross unrealized losses less than 12 months	0
Gross unrealized losses 12 months or longer	0
Estimated fair value	1,550
Short-term investments
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	140,277	140,676
Gross unrealized gains	44	60
Gross unrealized losses less than 12 months	(78)	(41)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	140,243	140,695
Short-term investments | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	23,472	25,430
Gross unrealized gains	0	1
Gross unrealized losses less than 12 months	0	0
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	23,472	25,431
Short-term investments | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	16,494	13,607
Gross unrealized gains	0	4
Gross unrealized losses less than 12 months	(34)	(8)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	16,460	13,603
Short-term investments | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	21,214	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	21,214	12,849
Short-term investments | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	57,469	58,753
Gross unrealized gains	39	43
Gross unrealized losses less than 12 months	(29)	(18)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	57,479	58,778
Short-term investments | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	20,829	22,146
Gross unrealized gains	5	12
Gross unrealized losses less than 12 months	(15)	(12)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	20,819	22,146
Short-term investments | Non-U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		3,403
Gross unrealized gains		0
Gross unrealized losses less than 12 months		(3)
Gross unrealized losses 12 months or longer		0
Estimated fair value		3,400
Short-term investments | Others
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	799	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	$ 799	$ 4,488