Senior Notes Payable (Details Textual) (USD $) In Thousands, unless otherwise specified	6 Months Ended				3 Months Ended	6 Months Ended			1 Months Ended
	Apr. 30, 2013 debtissuances	Apr. 30, 2012	Oct. 31, 2012	Apr. 30, 2013 Senior Notes Issued for Cash [Member]	Jul. 31, 2013 4.375% Senior Notes due 2023 [Member]	Apr. 30, 2013 4.375% Senior Notes due 2023 [Member]	May 03, 2013 4.375% Senior Notes due 2023 [Member]	Apr. 03, 2013 4.375% Senior Notes due 2023 [Member]	Nov. 30, 2012 Six Point Eight Seven Five Percent Senior Notes Due Two Thousand and Twelve [Member]	Nov. 22, 2002 Six Point Eight Seven Five Percent Senior Notes Due Two Thousand and Twelve [Member]
Debt Instrument [Line Items]
Number of issuances of senior debt	8
Senior Note Payable (Textual) [Abstract]
Issued Senior Notes	$ 2,322,397		$ 2,080,463	$ 2,330,000			$ 100,000	$ 300,000
Repayments of Senior Debt	59,068								59,068
Debt Instrument, Interest Rate, Stated Percentage								4.375%		6.875%
Par value of senior note issuance								103.00%
Proceeds from Issuance of Senior Long-term Debt	$ 298,050	$ 296,227			$ 102,333	$ 298,050