Shareholders' Equity - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended
May 31, 2012	Nov. 30, 2011
Stockholders Equity [Line Items]
Share repurchase authorized amount	$ 100.0	$ 100.0

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