Other Comprehensive Income (Loss) Other Comprehensive Income (Loss) - Reclassifications from AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Reclassification adjustment for sales of available for-sale securities, net of tax	$ 0	$ (58)

Amount after tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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