Short-term and Long-term Investments (Details) - USD ($) $ in Thousands	Jul. 31, 2015	Oct. 31, 2014
Long Term Investments
Amortized Cost	$ 230,172
Estimated Fair Value	230,228
U.S. government obligations
Long Term Investments
Amortized Cost	175,190	$ 160,198
Gross Unrealized Gains	56	70
Gross Unrealized Losses	0	0
Estimated Fair Value	175,246	160,268
U.S. government obligations \| Short-term investments
Long Term Investments
Amortized Cost	105,041	110,182
Gross Unrealized Gains	44	29
Gross Unrealized Losses	0	0
Estimated Fair Value	105,085	110,211
U.S. government obligations \| Other Long-term investments
Long Term Investments
Amortized Cost	70,149	50,016
Gross Unrealized Gains	12	41
Gross Unrealized Losses	0	0
Estimated Fair Value	70,161	50,057
Commercial paper
Long Term Investments
Amortized Cost	54,982	29,994
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	54,982	29,994
Commercial paper \| Short-term investments
Long Term Investments
Amortized Cost	54,982	29,994
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 54,982	$ 29,994

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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