Note 10 - Geographical Information - Revenue by Geographic Areas (Details) - USD ($)	3 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Operating Revenues	$ 47,697,373	$ 30,493,253
UNITED STATES
Operating Revenues	40,801,228	28,231,252
Non-US [Member]
Operating Revenues	$ 6,896,145	$ 2,262,001

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration