Other Information about Companys Restricted Share Awards (Detail) (Restricted Stock, USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of awards vested during the period	$ 3,826	$ 3,828
Pre-tax unrecognized compensation expense, net of estimated forfeitures as of September 30, 2012	$ 3,845
Weighted-average period (in years) to be recognized as expense	1 year 9 months 18 days

The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

-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 c(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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Period Type:	duration