Subsequent Events - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	1 Months Ended
Mar. 31, 2013	May 06, 2013 Subsequent Event 2012 Long Term Incentive Plan	Apr. 12, 2013 Subsequent Event 2012 Long Term Incentive Plan
Subsequent Event [Line Items]
Share-based compensation arrangement by Share-based payment award, options, grants in period		30,000	29,000
Fair value of stock option		$ 284	$ 282

Net number of share options (or share units) granted during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iv)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(d)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration