Fair Value Measurements - Additional Information (Detail) (Mutual funds, USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Fair Value, Inputs, Level 1
Assets, fair value disclosure, recurring	$ 0.8
Fair Value, Inputs, Level 2
Assets, fair value disclosure, recurring	$ 3.3

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

No definition available.

Name:	us-gaap_AssetsFairValueDisclosureRecurring
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant