Goodwill and Intangible Assets - Schedule of Acquired Intangible Assets, Other than Goodwill (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Mar. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 8,212	$ 8,055
Accumulated Amortization	6,580	5,813
Estimated amortization expense	1,632	2,242
MSRs [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	938	781
Accumulated Amortization	261	177
Estimated amortization expense	677	604
Core deposit intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7,274	7,274
Accumulated Amortization	6,319	5,636
Estimated amortization expense	$ 955	$ 1,638