Note 7 - Stockholders' Equity (Details Textual) | Feb. 24, 2017$ / sharesshares | Dec. 16, 2016$ / shares | Aug. 03, 2016USD ($)$ / sharesshares | Jul. 26, 2016shares | Jul. 07, 2016$ / sharesshares | Jul. 31, 2016shares | Mar. 31, 2017USD ($)$ / sharesshares | Dec. 31, 2016USD ($)shares | Mar. 31, 2016USD ($) | Mar. 31, 2017USD ($)$ / sharesshares | Mar. 31, 2016USD ($)shares | May 05, 2017shares |
Stock Issued During Period, Shares, New Issues | | | 600,000 | | | | | | | | | |
Shares Issued, Price Per Share | $ / shares | | | $ 4.10 | | | | | | | | | |
Payments of Stock Issuance Costs | $ | | | $ 369,000 | | | | | | | | | |
Proceeds from Issuance of Common Stock | $ | | | $ 2,091,000 | | | | | | | $ 2,091,000 | $ 2,463,000 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares | | | | | | | | | | $ 2.09 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number | | | | | | | 4,828,721 | | | 4,828,721 | | |
Class Of Warrant Or Right Weighted Average Exercise Price Of Warrants Or Rights | $ / shares | | | | | | | $ 9.37 | | | $ 9.37 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised | | | | | | | | | | 4,130,192 | | |
Share Based Compensation Arrangements By Share Based Payment Award Warrants Exercised In Period, Weighted Average Exercise Price | $ / shares | | | | | | | | | | $ 9.60 | | |
Class of Warrant or Right, Exercisable, Intrinsic Value | $ | | | | | | | $ 0 | | | $ 0 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period | | | | | | | | | | 0 | 0 | |
Former Chief Executive Officer [Member] | General and Administrative Expense [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost | $ | | | | | | | | $ 539,000 | | | | |
Former Chief Financial Officer [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost | $ | | | | | | | 94,000 | | | | | |
Employee Stock Option [Member] | | | | | | | | | | | | |
Allocated Share-based Compensation Expense | $ | | | | | | | 247,000 | | $ 247,000 | $ 1,280,000 | $ 551,000 | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | | | | | | 251,325 | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ / shares | | | | | | | | | | $ 2.92 | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options | $ | | | | | | | $ 211,000 | | | $ 211,000 | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | | | | | | | | | | 2 years | | |
Employee Stock Option [Member] | Former Chief Executive Officer [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number | | | | | | | | 72,496 | | | | |
Employee Stock Option [Member] | Former Chief Financial Officer [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number | | | | | | | 16,248 | | | | | |
Employee Stock Option [Member] | Former Chief Executive Officer and Former Chief Financial Officer [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Pre-Modification of Agreement | | | | | | | | | | 90 days | | |
Employee Stock Option [Member] | Chief Operating Officer [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | 25,000 | | | | | | | | | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ / shares | $ 2.89 | | | | | | | | | | | |
Employee Stock Option [Member] | Interim Chief Executive Officer [Member] | | | | | | | | | | | | |
Number Of Installments | | 5 | | | | | | | | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ / shares | | $ 2.91 | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period | | 7 years | | | | | | | | | | |
Restricted Stock [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number | | | | | | | | | | 51,636 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | | | | 98,417 | | | | | | 247,168 | | |
Restricted Stock [Member] | Former Chief Executive Officer [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number | | | | | | | | 79,720 | | | | |
Restricted Stock [Member] | Former Chief Financial Officer [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number | | | | | | | 15,914 | | | | | |
Restricted Stock Units (RSUs) [Member] | Chief Operating Officer [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | 25,000 | | | | | | | | | | | |
Restricted Stock Units (RSUs) [Member] | Chief Operating Officer [Member] | Share-based Compensation Award, Tranche One [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 25.00% | | | | | | | | | | | |
Restricted Stock Units (RSUs) [Member] | Chief Operating Officer [Member] | Share-based Compensation Award, Tranche Two [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 25.00% | | | | | | | | | | | |
Restricted Stock Units (RSUs) [Member] | Chief Operating Officer [Member] | Share-based Compensation Award, Tranche Three [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 25.00% | | | | | | | | | | | |
Restricted Stock Units (RSUs) [Member] | Chief Operating Officer [Member] | Share-based Compensation Award, Tranche Four [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage | 25.00% | | | | | | | | | | | |
Employee Stock Options and Restricted Stock Units (RSUs) [Member] | Chief Operating Officer [Member] | | | | | | | | | | | | |
Number Of Installments | 4 | | | | | | | | | | | |
Short Term Plan [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period | | | | | | 118,288 | | | | | | |
Shares Paid for Tax Withholding for Share Based Compensation | | | | | | 46,879 | | | | | | |
Amended 2016 Plan [Member | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Accumulated Shares Issued | | | | | | | 255,942 | | | 255,942 | | |
Amended 2016 Plan [Member | Subsequent Event [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | | | | | | | | | | | | 600,000 |
The 2016 Plan [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | 156,100 | | | | | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ / shares | | | | | $ 2.86 | | | | | | | |
The 2016 Plan [Member] | Employee Stock Option [Member] | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period | | | | | 7 years | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Ratable Vesting Period | | | | | 180 days | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | | | | | 3 years | | | | | | | |