Fair Value Measurements (Details 1) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jul. 31, 2015	Oct. 31, 2014
Assets:
Assets measured at fair value	$ 819,958	$ 691,831
Liabilities:
Total liabilities measured at fair value	6,909	2,283
Cash equivalents
Assets:
Assets measured at fair value	583,893	500,008
Short-term investments
Assets:
Assets measured at fair value	160,067	140,205
Prepaid expenses and other
Assets:
Assets measured at fair value	5,837	1,561
Long-term investments
Assets:
Assets measured at fair value	70,161	50,057
Accrued liabilities
Liabilities:
Total liabilities measured at fair value	1,941	200
Other long-term obligations
Liabilities:
Other long-term obligations	4,968	2,083
Level 1
Assets:
Assets measured at fair value	538,895	440,013
Liabilities:
Total liabilities measured at fair value	0	0
Level 1 | Cash equivalents
Assets:
Assets measured at fair value	538,895	440,013
Level 2
Assets:
Assets measured at fair value	281,063	251,818
Liabilities:
Total liabilities measured at fair value	6,909	2,283
Level 2 | Cash equivalents
Assets:
Assets measured at fair value	44,998	59,995
Level 2 | Short-term investments
Assets:
Assets measured at fair value	160,067	140,205
Level 2 | Prepaid expenses and other
Assets:
Assets measured at fair value	5,837	1,561
Level 2 | Long-term investments
Assets:
Assets measured at fair value	70,161	50,057
Level 2 | Accrued liabilities
Liabilities:
Total liabilities measured at fair value	1,941	200
Level 2 | Other long-term obligations
Liabilities:
Other long-term obligations	4,968	2,083
Level 3
Assets:
Assets measured at fair value	0	0
Liabilities:
Total liabilities measured at fair value	$ 0	$ 0