Short-term and Long-term Investments (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2015	Oct. 31, 2014
Long Term Investments
Amortized Cost	$ 200,200
Estimated Fair Value	200,307us-gaap_AvailableForSaleSecurities
U.S. government obligations
Long Term Investments
Amortized Cost	170,214	160,198
Gross Unrealized Gains	107	70
Gross Unrealized Losses	0	0
Estimated Fair Value	170,321	160,268
Commercial paper
Long Term Investments
Amortized Cost	29,986	29,994
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	29,986	29,994
Short-term investments \| U.S. government obligations
Long Term Investments
Amortized Cost	115,129	110,182
Gross Unrealized Gains	39	29
Gross Unrealized Losses	0	0
Estimated Fair Value	115,168	110,211
Short-term investments \| Commercial paper
Long Term Investments
Amortized Cost	29,986	29,994
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	29,986	29,994
Other Long-term investments \| U.S. government obligations
Long Term Investments
Amortized Cost	55,085	50,016
Gross Unrealized Gains	68	41
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 55,153	$ 50,057

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.

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