Note 11 - Stockholders' equity (Detail) - Information about the outstanding and exercisable options (USD $)	12 Months Ended
	Dec. 31, 2012
Range of $3.00 - 3.99 [Member] | Minimum [Member]
Exercise Price Range, lower range	$ 3.00
Range of $3.00 - 3.99 [Member] | Maximum [Member]
Exercise Price Range, upper range	$ 3.99
Range of $3.00 - 3.99 [Member]
Options outstanding, number outstanding (in Shares)	72,000
Options outstanding, weighted average remaining contractual	4 years 346 days
Options outstanding, weighted average exercise price	$ 3.65
Options outstanding, intrinsic value (in Dollars)	$ 428,400
Options exercisable, number exercisable (in Shares)	72,000
Options exercisable, weighted average exercise price	$ 3.65
Options exercisable, intrinsic value (in Dollars)	428,400
Range of $4.00 - 4.49 [Member] | Minimum [Member]
Exercise Price Range, lower range	$ 4.00
Range of $4.00 - 4.49 [Member] | Maximum [Member]
Exercise Price Range, upper range	$ 4.49
Range of $4.00 - 4.49 [Member]
Options outstanding, number outstanding (in Shares)	15,930
Options outstanding, weighted average remaining contractual	357 days
Options outstanding, weighted average exercise price	$ 4.25
Options outstanding, intrinsic value (in Dollars)	85,226
Options exercisable, number exercisable (in Shares)	15,930
Options exercisable, weighted average exercise price	$ 4.25
Options exercisable, intrinsic value (in Dollars)	85,226
Range of $4.50 - 4.99 [Member] | Minimum [Member]
Exercise Price Range, lower range	$ 4.50
Range of $4.50 - 4.99 [Member] | Maximum [Member]
Exercise Price Range, upper range	$ 4.99
Range of $4.50 - 4.99 [Member]
Options outstanding, number outstanding (in Shares)	100,000
Options outstanding, weighted average remaining contractual	4 years 284 days
Options outstanding, weighted average exercise price	$ 4.62
Options outstanding, intrinsic value (in Dollars)	498,000
Options exercisable, number exercisable (in Shares)	62,500
Options exercisable, weighted average exercise price	$ 4.62
Options exercisable, intrinsic value (in Dollars)	311,250
Range of $5.00 - 5.99 [Member] | Minimum [Member]
Exercise Price Range, lower range	$ 5.00
Range of $5.00 - 5.99 [Member] | Maximum [Member]
Exercise Price Range, upper range	$ 5.99
Range of $5.00 - 5.99 [Member]
Options outstanding, number outstanding (in Shares)	6,650
Options outstanding, weighted average remaining contractual	1 year 29 days
Options outstanding, weighted average exercise price	$ 5.90
Options outstanding, intrinsic value (in Dollars)	24,605
Options exercisable, number exercisable (in Shares)	6,650
Options exercisable, weighted average exercise price	$ 5.90
Options exercisable, intrinsic value (in Dollars)	24,605
Range of $6.00 - 7.99 [Member] | Minimum [Member]
Exercise Price Range, lower range	$ 6.00
Range of $6.00 - 7.99 [Member] | Maximum [Member]
Exercise Price Range, upper range	$ 7.99
Range of $6.00 - 7.99 [Member]
Options outstanding, number outstanding (in Shares)	9,800
Options outstanding, weighted average remaining contractual	8 years 14 days
Options outstanding, weighted average exercise price	$ 7.90
Options outstanding, intrinsic value (in Dollars)	16,660
Options exercisable, number exercisable (in Shares)	9,800
Options exercisable, weighted average exercise price	$ 7.90
Options exercisable, intrinsic value (in Dollars)	16,660
Range of $8.00 - 11.99 [Member] | Minimum [Member]
Exercise Price Range, lower range	$ 8.00
Range of $8.00 - 11.99 [Member] | Maximum [Member]
Exercise Price Range, upper range	$ 11.99
Range of $8.00 - 11.99 [Member]
Options outstanding, number outstanding (in Shares)	200
Options outstanding, weighted average remaining contractual	9 years
Options outstanding, weighted average exercise price	$ 11.51
Options outstanding, intrinsic value (in Dollars)	0
Options exercisable, number exercisable (in Shares)	200
Options exercisable, weighted average exercise price	$ 11.51
Options exercisable, intrinsic value (in Dollars)	$ 0