Financial Assets and Liabilities - Short-term investments (Details) - USD ($) $ in Thousands		Jul. 31, 2016	Oct. 31, 2015
Cash equivalents
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		$ 405,470	$ 239,473
Gross unrealized gains		0	0
Gross unrealized losses less than 12 months		0	(1)
Gross unrealized losses 12 months or longer		0	0
Estimated fair value	[1]	405,470	239,472
Cash equivalents | Money market funds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		403,070	233,839
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]	403,070	233,839
Cash equivalents | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost			1,834
Gross unrealized gains			0
Gross unrealized losses less than 12 months			0
Gross unrealized losses 12 months or longer			0
Estimated fair value	[1]		1,834
Cash equivalents | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		2,400	3,500
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]	2,400	3,500
Cash equivalents | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost			300
Gross unrealized gains			0
Gross unrealized losses less than 12 months			(1)
Gross unrealized losses 12 months or longer			0
Estimated fair value	[1]		299
Short-term investments
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		143,478	128,774
Gross unrealized gains		82	33
Gross unrealized losses less than 12 months		(18)	(60)
Gross unrealized losses 12 months or longer		0	0
Estimated fair value	[1]	143,542	128,747
Short-term investments | Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		20,682	12,129
Gross unrealized gains		0	0
Gross unrealized losses less than 12 months		(1)	0
Gross unrealized losses 12 months or longer		0	0
Estimated fair value	[1]	20,681	12,129
Short-term investments | U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		17,011	12,615
Gross unrealized gains		9	3
Gross unrealized losses less than 12 months		(1)	(4)
Gross unrealized losses 12 months or longer		0	0
Estimated fair value	[1]	17,019	12,614
Short-term investments | Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		700	1,403
Gross unrealized gains		0	1
Gross unrealized losses less than 12 months		0	(1)
Gross unrealized losses 12 months or longer		0	0
Estimated fair value	[1]	700	1,403
Short-term investments | Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		17,500	9,800
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]	17,500	9,800
Short-term investments | Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		61,245	67,201
Gross unrealized gains		62	27
Gross unrealized losses less than 12 months		(6)	(40)
Gross unrealized losses 12 months or longer		0	0
Estimated fair value	[1]	61,301	67,188
Short-term investments | Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		20,430	24,619
Gross unrealized gains		11	2
Gross unrealized losses less than 12 months		(10)	(13)
Gross unrealized losses 12 months or longer		0	0
Estimated fair value	[1]	20,431	24,608
Short-term investments | Non-U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		1,003	1,007
Gross unrealized gains		0	0
Gross unrealized losses less than 12 months		0	(2)
Gross unrealized losses 12 months or longer		0	0
Estimated fair value	[1]	1,003	$ 1,005
Short-term investments | Other
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, cost		4,907
Gross unrealized gains		0
Gross unrealized losses less than 12 months		0
Gross unrealized losses 12 months or longer		0
Estimated fair value	[1]	$ 4,907

[1] See Note 6. Fair Value Measures for further discussion on fair values of cash equivalents and short-term investments.