Subsequent Event (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	12 Months Ended	0 Months Ended
Dec. 15, 2011	Oct. 31, 2012	Dec. 05, 2012 Subsequent Event [Member]
Subsequent Event [Line Items]
Share repurchase program, maximum amount authorized	$ 150.0		$ 300.0
Share repurchase program, remaining authorized amount		$ 78.9	$ 228.9

The remaining repurchase amount authorized by an entity's Board of Directors under a stock repurchase plan.

No definition available.

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration