Fair Value Measurements Fair Value, Assets Measured on Recurring Basis, Valuation Techniques (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Securities Available-for-Sale		$ 391	$ 403
Mortgage servicing rights		183	192
Fair Value, Measurements, Recurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Securities Available-for-Sale		55,087	59,011
Mortgage servicing rights		183	192
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Securities Available-for-Sale		391	403
Mortgage servicing rights			192
Fair Value, Measurements, Recurring | Mortgage Backed Securities, Other | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 45	$ 45	$ 45	$ 45
Fair Value Measurements, Valuation Techniques		Cost	Cost
Fair Value Measurements, Significant Assumptions		n/a	n/a
Fair Value, Measurements, Recurring | Other investments | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 346	$ 358	360	148
Fair Value Measurements, Valuation Techniques		Cost	Cost
Fair Value Measurements, Significant Assumptions		n/a	n/a
Fair Value, Measurements, Recurring | Other Assets | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 183	$ 192	$ 193	$ 201
Mortgage servicing rights		$ 183	$ 192
Fair Value Measurements, Valuation Techniques		Discounted Cash Flow	Discounted Cash Flow
Fair Value Measurements, Significant Assumptions	[1]	Weighted Average Constant Prepayment Rate(1)	Weighted Average Constant Prepayment Rate(1)
Fair Value Inputs, Prepayment Rate		19.47%	22.37%

[1] (1) Represents annualized loan repayment rate assumptions