Pending Litigation (Details) (USD $)	1 Months Ended	3 Months Ended
	Feb. 28, 2009	Oct. 30, 2011
Loss Contingencies [Line Items]
Amount paid in litigation settlement		$ 7,400,000
Litigation related expense	327,000
Underwriter Defendants [Member] | Pending or Threatened Litigation [Member]
Loss Contingencies [Line Items]
Amount paid in litigation settlement	(486,000,000)
Issuer Defendants [Member]
Loss Contingencies [Line Items]
Amount paid in litigation settlement	$ (100,000,000)