Financial Assets and Liabilities - Short-term investments (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Oct. 31, 2016
Cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	$ 513,960	$ 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	513,960	504,972
Cash equivalents | Money market funds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	510,086	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	510,086	499,274
Cash equivalents | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	2,274	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	2,274	1,498
Cash equivalents | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	1,600	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	1,600	4,200
Short-term investments
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	147,522	140,676
Gross unrealized gains	55	60
Gross unrealized losses less than 12 months	(65)	(41)
Gross unrealized losses 12 months or longer	(4)	0
Estimated fair value	147,508	140,695
Short-term investments | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	23,507	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	23,507	25,431
Short-term investments | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	17,982	13,607
Gross unrealized gains	2	4
Gross unrealized losses less than 12 months	(27)	(8)
Gross unrealized losses 12 months or longer	(4)	0
Estimated fair value	17,953	13,603
Short-term investments | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	22,017	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	22,017	12,849
Short-term investments | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	61,337	58,753
Gross unrealized gains	47	43
Gross unrealized losses less than 12 months	(23)	(18)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	61,361	58,778
Short-term investments | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost	21,180	22,146
Gross unrealized gains	4	12
Gross unrealized losses less than 12 months	(15)	(12)
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	21,169	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	1,499	4,488
Gross unrealized gains	2	0
Gross unrealized losses less than 12 months	0	0
Gross unrealized losses 12 months or longer	0	0
Estimated fair value	$ 1,501	$ 4,488