Commitments and Contingent Liabilities - Additional Information (Detail) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2013 USD ($)	Jun. 30, 2013 GBP (£)	Dec. 31, 2010 USD ($)	Dec. 31, 2010 GBP (£)
Other Liabilities Disclosure [Abstract]
Outstanding standby and commercial letters of credit	$ 18,255
Government grants awarded			1,325	850
Government grants received	1,083	680
Recorded liability	$ 0

Revenue earned during the period from non-repayable sum of money awarded to an entity to carry out a specific purpose as provided in grant agreements.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(e))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Name:	us-gaap_RevenueFromGrants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration