Office Properties and Equipment, Net Office Properties and Equipment, Net Text Tag (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2020	Mar. 31, 2019
Property, Plant and Equipment [Line Items]
Depreciation		$ 965	$ 793
Gain on sale of building	$ 9,600	0	616
Cumulative Effect of New Accounting Principle		$ 5,300
Crown Heights [Domain]
Property, Plant and Equipment [Line Items]
Deferred Gain on Sale of Property			468
Main Office [Domain]
Property, Plant and Equipment [Line Items]
Deferred Gain on Sale of Property			$ 4,900