Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Jul. 31, 2013	Oct. 31, 2012
Long Term Investments
U.S. government obligations	$ 115,003
U.S. government obligations [Member]
Long Term Investments
Amortized Cost	114,960	49,987
Gross Unrealized Gains	43	70
Gross Unrealized Losses	0	0
U.S. government obligations	115,003	50,057
Short-term Investments [Member] | U.S. government obligations [Member]
Long Term Investments
Amortized Cost	99,964	49,987
Gross Unrealized Gains	17	70
Gross Unrealized Losses	0	0
U.S. government obligations	99,981	50,057
Other Long-term Investments [Member] | U.S. government obligations [Member]
Long Term Investments
Amortized Cost	14,996	0
Gross Unrealized Gains	26	0
Gross Unrealized Losses	0	0
U.S. government obligations	$ 15,022	$ 0