Accounts Receivable - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts Receivable Textual [Abstract]
Accounts receivable unbilled amounts	$ 2.4	$ 2.7

Amount of unbilled receivables under long-term contracts that have not been billed and were not billable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 910

-SubTopic 310

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6471494&loc=d3e49336-109356

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