7. Shareholders' equity (Detail) - Changes in Shareholders' Equity activity (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Balance at			$ 35,313
Net income	508	1,442	1,716	3,267
Share-based compensation expense			284	299
Proceeds from issuance of shares from exercise of stock options			145	657
Issuance of deferred stock units			134
Tax benefit related to employee stock sales and vesting of restricted stock			42
Foreign currency translation adjustment	3		3
Purchases of common stock for treasury			(5,151)	(1,843)
Balance at	$ 32,486		$ 32,486