Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2014 LegalMatter
Commitment And Contingencies [Line Items]
Estimated defect repairing expense	$ 0.2
Material legal proceedings pending	0

Number of pending claims pertaining to a loss contingency.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Name:	us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant