Description of Basis of Consolidation and Presentation - Additional Information (Detail) $ in Millions	3 Months Ended
Mar. 31, 2015 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Settlement of fund for eligible participants	$ (12.3)

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

No definition available.

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