Note 3 - Stock-Based Compensation and Stock Option Activity (Detail) - Stock Option Activity Under Equity Incentive Plan (USD $)	3 Months Ended
	Mar. 31, 2013
Total options outstanding	1,097,236
Total options outstanding (in Dollars per share)	$ 4.58
Options granted	80,000
Options granted (in Dollars per share)	$ 3.56
Options exercised	(53,829)
Options exercised (in Dollars per share)	$ 2.56
Options forfeited and cancelled	(29,925)
Options forfeited and cancelled (in Dollars per share)	$ 3.54
Options Outstanding [Member]
Total options outstanding	1,093,482
Total options outstanding (in Dollars per share)	$ 4.63
Options Exercisable [Member]
Options exercisable at March 31, 2013	662,308
Options exercisable at March 31, 2013 (in Dollars per share)	$ 5.40
Options exercisable at March 31, 2013	4 years 6 months
Options exercisable at March 31, 2013 (in Dollars)	$ 179,082	[1]
Options vested and expected to vest at March 31, 2013	4 years 6 months
Options Vested And Expected To Vest [Member]
Options exercisable at March 31, 2013	6 years 7 days
Options vested and expected to vest at March 31, 2013	1,057,176
Options vested and expected to vest at March 31, 2013 (in Dollars per share)	$ 4.68
Options vested and expected to vest at March 31, 2013	6 years 7 days
Options vested and expected to vest at March 31, 2013 (in Dollars)	$ 406,317	[1]

[1] Aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the quoted price of Onvia's common stock of $3.83 at March 31, 2013 for options that were in-the-money at March 31, 2013. The number of in-the-money options outstanding and exercisable at March 31, 2013 was 564,298 and 205,315, respectively.