Net Periodic Cost for U.K Plan and Japan Plan (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
UNITED KINGDOM
Components of the net periodic pension cost:
Interest cost	$ 1,359	$ 1,486	$ 1,447
Expected return on plan assets	(1,270)	(1,576)	(1,467)
Amortization of actuarial losses	392	224	204
Net periodic pension cost	481	134	184
JAPAN
Components of the net periodic pension cost:
Service cost	121	106	115
Interest cost	15	18	14
Amortization of the unrecognized transition obligation	37	40	42
Amortization of prior service cost	3	2
Net periodic pension cost	$ 176	$ 166	$ 171