Note 2 - Revenue Recognition - Disaggregation of Revenue by Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues	$ 75,436	$ 69,936	$ 171,640	$ 149,924
Revenues, percentage	100.00%	100.00%	100.00%	100.00%
Revenues, variance	$ 5,500		$ 21,716
Revenues, variance, percentage	7.90%		14.50%
Internet [Member]
Revenues	$ 62,697	$ 58,453	$ 144,208	$ 125,476
Revenues, percentage	83.10%	83.60%	84.00%	83.70%
Revenues, variance	$ 4,244		$ 18,732
Revenues, variance, percentage	7.30%		14.90%
Contact Center [Member]
Revenues	$ 12,739	$ 11,483	$ 27,432	$ 24,448
Revenues, percentage	16.90%	16.40%	16.00%	16.30%
Revenues, variance	$ 1,256		$ 2,984
Revenues, variance, percentage	10.90%		12.20%
Reorder Customer [Member]
Revenues	$ 67,761	$ 61,851	$ 148,186	$ 129,593
Revenues, percentage	89.80%	88.40%	86.30%	86.40%
Revenues, variance	$ 5,910		$ 18,593
Revenues, variance, percentage	9.60%		14.30%
New Order Customer [Member]
Revenues	$ 7,675	$ 8,085	$ 23,454	$ 20,331
Revenues, percentage	10.20%	11.60%	13.70%	13.60%
Revenues, variance	$ (410)		$ 3,123
Revenues, variance, percentage	(5.10%)		15.40%