Other Events (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
Apr. 30, 2012
Stock buyback program announced amount	$ 200
Previous Stock Repurchase Authorization [Member]
Stock buyback program announced amount	$ 100

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

No definition available.

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