Subsequent Events (Details) (USD $)						2 Months Ended
	Sep. 30, 2012	May 31, 2011	Sep. 30, 2012 Two Thousand Twenty Six Notes Member	Oct. 31, 2012 Subsequent Event [Member]	Oct. 30, 2012 Subsequent Event [Member]	Nov. 02, 2012 Subsequent Event [Member] Two Thousand Twenty Six Notes Member	Oct. 31, 2012 Line of Credit [Member] Subsequent Event [Member]
Subsequent Event [Line Items]
Stated interest rate			3.95%
Convertion ration (in shares)			42.624
Principal amount of debt converted						$ 100,600,000
Principal amount of debt						38,100,000
Revolving credit facility borrowing capacity		$ 450,000,000		$ 500,000,000	$ 450,000,000
Basis spread on variable rate	1.50%						1.175%