Benefit Obligation, Amounts Recognized Company's Financial Statements and Principal Assumptions (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Change in projected benefit obligation:
Benefit obligation at beginning of year	$ 1,142	$ 688	$ 377
Service cost	317	263	228
Interest cost	45	36	23
Actuarial (gains)/losses	129	155	60
Net periodic benefit cost	491	454	311
Benefit obligation at end of year	1,633	1,142	688
W.E.T.
Change in projected benefit obligation:
Benefit obligation at beginning of year	4,250	4,280
Service cost	199	7
Interest cost	195	118
Paid pension distributions	(277)	(167)
Actuarial (gains)/losses	912	(55)
Past service cost		67
Exchange rate impact	113
Benefit obligation at end of year	$ 5,392	$ 4,250