Organization and Basis of Presentation - Additional Information (Detail) (Contran Corporation [Member], USD $)	Mar. 31, 2013	Apr. 30, 2013 Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Ownership Percentage	88.00%	90.40%
Threshold required to make action under the Delaware General Corporation Law	90.00%
Share conversion price per share	$ 9

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant