Note 11 - Stock Based Compensation (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018	Mar. 31, 2017	Nov. 30, 2013	Oct. 10, 2012
Share Price								$ 10
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance	28,161		28,161		19,440	36,220
2013 Equity Incentive Plan [Member]
Stock or Unit Option Plan Expense	$ 61,514	$ 57,392	$ 123,028	$ 114,784
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total	$ 207,678		$ 207,678
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			2 years
Share Price	$ 14.31		$ 14.31
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 117,650		$ 117,650
Restricted Stock or Unit Expense	$ 64,089	$ 57,819	$ 128,178	$ 115,638
2013 Equity Incentive Plan [Member] \| Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized							148,120
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance	92,701		92,701
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures, Total			268,204
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			5 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			20.00%
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total	$ 222,681		$ 222,681
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			1 year 328 days
2013 Equity Incentive Plan [Member] \| Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized							370,300
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			5 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			20.00%
2013 Equity Incentive Plan [Member] \| Employee Stock Option [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period			10 years

Hamilton Bancorp, Inc. 10-Q