Defined Benefit Pension Obligation - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Schedule Of Defined Contribution Plans Disclosures [Line Items]
Prior service cost for defined benefit pension plan, future amortization cost from accumulated other comprehensive income (loss)	$ 275,000
Expected contribution to the pension plan	$ 1,800,000

Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration