Fair Value Measurements - Balance Sheet Items (Details) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Oct. 31, 2014	Oct. 31, 2013
Level 1
Assets:
Total assets measured at fair value	$ 440,013	$ 254,330
Liabilities:
Total liabilities measured at fair value	0	0
Level 2
Assets:
Total assets measured at fair value	251,818	160,007
Liabilities:
Total liabilities measured at fair value	2,283	442
Level 3
Assets:
Total assets measured at fair value	0	2,740
Liabilities:
Total liabilities measured at fair value	0	0
Total
Assets:
Total assets measured at fair value	691,831	417,077
Liabilities:
Total liabilities measured at fair value	2,283	442
Cash and Cash Equivalents | Level 1
Assets:
Cash equivalents	440,013	252,241
Cash and Cash Equivalents | Level 2
Assets:
Cash equivalents	59,995	19,997
Cash and Cash Equivalents | Level 3
Assets:
Cash equivalents	0	0
Cash and Cash Equivalents | Total
Assets:
Cash equivalents	500,008	272,238
Short-term Investments | Level 1
Assets:
Short-term investments	0	0
Short-term Investments | Level 2
Assets:
Short-term investments	140,205	124,979
Short-term Investments | Level 3
Assets:
Short-term investments	0	0
Short-term Investments | Total
Assets:
Short-term investments	140,205	124,979
Prepaid Expenses and Other Current Assets | Level 1
Assets:
Prepaid expenses and other	0	52
Prepaid Expenses and Other Current Assets | Level 2
Assets:
Prepaid expenses and other	1,561	0
Prepaid Expenses and Other Current Assets | Level 3
Assets:
Prepaid expenses and other	0	0
Prepaid Expenses and Other Current Assets | Total
Assets:
Prepaid expenses and other	1,561	52
Marketable Securities Noncurrent | Level 1
Assets:
Long-term investments	0	0
Marketable Securities Noncurrent | Level 2
Assets:
Long-term investments	50,057	15,031
Marketable Securities Noncurrent | Level 3
Assets:
Long-term investments	0	0
Marketable Securities Noncurrent | Total
Assets:
Long-term investments	50,057	15,031
Other Long-Term Asset | Level 1
Assets:
Other long-term assets		2,037
Other Long-Term Asset | Level 2
Assets:
Other long-term assets		0
Other Long-Term Asset | Level 3
Assets:
Other long-term assets		2,740
Other Long-Term Asset | Total
Assets:
Other long-term assets		4,777
Accrued Liabilities | Level 1
Liabilities:
Accrued liabilities	0	0
Accrued Liabilities | Level 2
Liabilities:
Accrued liabilities	200	442
Accrued Liabilities | Level 3
Liabilities:
Accrued liabilities	0	0
Accrued Liabilities | Total
Liabilities:
Accrued liabilities	200	442
Other Long-Term Liabilities | Level 1
Liabilities:
Other long-term obligations	0
Other Long-Term Liabilities | Level 2
Liabilities:
Other long-term obligations	2,083
Other Long-Term Liabilities | Level 3
Liabilities:
Other long-term obligations	0
Other Long-Term Liabilities | Total
Liabilities:
Other long-term obligations	$ 2,083