Subsequent Event - Additional Information (Detail) In Billions, unless otherwise specified	Jul. 30, 2007	Feb. 12, 2013 Subsequent event
Subsequent Event [Line Items]
Share repurchase program authorized amount	2.0	1.0

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

No definition available.

Name:	us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant