Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Accounting Policies [Abstract]
Amortization of intangible assets	10 years
Unrealized gain on available for sale securities	$ 3,295	$ 4,019
Minimum pension liability adjustment	$ 2,055	$ 1,818

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The net amount of gross unrealized gains (losses) for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563

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- Definition

Weighted average period before the next renewal or extension (both explicit and implicit) for intangible assets that have been renewed or extended, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=7658586&loc=d3e16323-109275

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- Definition

Net of tax amount, before reclassification adjustments, of the change in accumulated other comprehensive income (loss) related to pension and other postretirement benefit plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (i-k)

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

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