Inventories - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Inventories Net [Line Items]
Progress payments to vendor	$ 8.1	$ 8.1

The amount of assets, typically cash, provided to suppliers of goods in advance of receipt and acceptance, or services (such as research facilities, lawyers or consultants), which is held by such parties until the entity either effects full payment (including applying the retainer) or obtains release from liability.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.8,17)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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