Supplemental Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplemental Cash Flow Information [Abstract]
Taxes paid	$ 2,825	$ 1,953	$ 1,894
Interest paid	27	51	19
Non-cash investing and financing activities:
Fixed assets acquired with accounts payable or accrued liabilities	940	1,611	906
Unclaimed merger consideration	$ 1,575	$ 4,026	$ 0