7. Shareholders' equity (Detail) - Changes in Shareholders' Equity activity (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Balance at			$ 35,313
Net income	23	839	1,739	4,106
Share-based compensation expense			402	445
Proceeds from stock option exercises			145	863
Issuance of deferred stock units			134
Incremental tax benefits from stock options exercised			42	439
Foreign currency translation adjustment	16		16
Purchases of common stock for treasury			(5,563)	(2,075)
Balance at	$ 32,228		$ 32,228