Investments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Restricted investments	$ 15,485us-gaap_RestrictedInvestmentsNoncurrent	$ 15,485us-gaap_RestrictedInvestmentsNoncurrent

This element represents the noncurrent portion of investments which are not defined as or included in marketable (debt, equity, or other) securities that are pledged or subject to withdrawal restrictions.

No definition available.

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